diff --git a/xml/System.Reflection.PortableExecutable/PEDirectoriesBuilder.xml b/xml/System.Reflection.PortableExecutable/PEDirectoriesBuilder.xml
index af9abbbcc2b..47b3f40d398 100644
--- a/xml/System.Reflection.PortableExecutable/PEDirectoriesBuilder.xml
+++ b/xml/System.Reflection.PortableExecutable/PEDirectoriesBuilder.xml
@@ -17,7 +17,7 @@
   </Base>
   <Interfaces />
   <Docs>
-    <summary>To be added.</summary>
+    <summary>Builds PE directories.</summary>
     <remarks>To be added.</remarks>
   </Docs>
   <Members>
@@ -37,7 +37,7 @@
       </AssemblyInfo>
       <Parameters />
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Initializes an instance of the <see cref="T:System.Reflection.PortableExecutable.PEDirectoriesBuilder" /> class.</summary>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -60,8 +60,8 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>The address of the entry point relative to the image base when the PE file is loaded into memory.</summary>
+        <value>For program images, this is the starting address. For device drivers, this is the address of the initialization function. An entry point is optional for DLLs. When no entry point is present, this field must be zero.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -84,9 +84,17 @@
         <ReturnType>System.Reflection.PortableExecutable.DirectoryEntry</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>The base relocation table image directory entry.</summary>
+        <value>A directory entry instance.</value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_BASERELOC`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="BoundImportTable">
@@ -108,9 +116,17 @@
         <ReturnType>System.Reflection.PortableExecutable.DirectoryEntry</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>The bound import image directory entry.</summary>
+        <value>A directory entry instance.</value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_BOUND_IMPORT`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="CopyrightTable">
@@ -132,9 +148,17 @@
         <ReturnType>System.Reflection.PortableExecutable.DirectoryEntry</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>The copyright/architecture image directory entry.</summary>
+        <value>A directory entry instance.</value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_COPYRIGHT` or `IMAGE_DIRECTORY_ENTRY_ARCHITECTURE`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="CorHeaderTable">
@@ -156,9 +180,17 @@
         <ReturnType>System.Reflection.PortableExecutable.DirectoryEntry</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>The COM descriptortable image directory entry.</summary>
+        <value>A directory entry instance.</value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_COM_DESCRIPTOR`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="DebugTable">
@@ -180,9 +212,17 @@
         <ReturnType>System.Reflection.PortableExecutable.DirectoryEntry</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>The debug table image directory entry.</summary>
+        <value>A directory entry instance.</value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_DEBUG`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="DelayImportTable">
@@ -204,9 +244,17 @@
         <ReturnType>System.Reflection.PortableExecutable.DirectoryEntry</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>The delay import table image directory entry.</summary>
+        <value>A directory entry instance.</value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_DELAY_IMPORT`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="ExceptionTable">
@@ -228,9 +276,17 @@
         <ReturnType>System.Reflection.PortableExecutable.DirectoryEntry</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>The exception table image directory entry.</summary>
+        <value>A directory entry instance.</value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_EXCEPTION`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="ExportTable">
@@ -252,9 +308,17 @@
         <ReturnType>System.Reflection.PortableExecutable.DirectoryEntry</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>The export table image directory entry.</summary>
+        <value>A directory entry instance.</value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_EXPORT`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="GlobalPointerTable">
@@ -276,9 +340,17 @@
         <ReturnType>System.Reflection.PortableExecutable.DirectoryEntry</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>The global pointer table image directory entry.</summary>
+        <value>A directory entry instance.</value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_GLOBALPTR`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="ImportAddressTable">
@@ -300,9 +372,17 @@
         <ReturnType>System.Reflection.PortableExecutable.DirectoryEntry</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>The import address table (IAT) image directory entry.</summary>
+        <value>A directory entry instance.</value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_IAT`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="ImportTable">
@@ -324,9 +404,17 @@
         <ReturnType>System.Reflection.PortableExecutable.DirectoryEntry</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>The import table image directory entry.</summary>
+        <value>A directory entry instance.</value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_IMPORT`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="LoadConfigTable">
@@ -348,9 +436,17 @@
         <ReturnType>System.Reflection.PortableExecutable.DirectoryEntry</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>The load configuration table image directory entry.</summary>
+        <value>A directory entry instance.</value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_LOAD_CONFIG`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="ResourceTable">
@@ -372,9 +468,17 @@
         <ReturnType>System.Reflection.PortableExecutable.DirectoryEntry</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>The resource table image directory entry.</summary>
+        <value>A directory entry instance.</value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_RESOURCE`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="ThreadLocalStorageTable">
@@ -396,9 +500,17 @@
         <ReturnType>System.Reflection.PortableExecutable.DirectoryEntry</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>The thread local storage (TLS) table image directory entry.</summary>
+        <value>A directory entry instance.</value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_TLS`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
   </Members>
diff --git a/xml/System.Reflection.PortableExecutable/PEHeader.xml b/xml/System.Reflection.PortableExecutable/PEHeader.xml
index 8914a7275fb..e7a42912bec 100644
--- a/xml/System.Reflection.PortableExecutable/PEHeader.xml
+++ b/xml/System.Reflection.PortableExecutable/PEHeader.xml
@@ -44,9 +44,17 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>Gets the address of the entry point relative to the image base when the PE file is loaded into memory.</summary>
+        <value>The address of the entry point relative to the image base.</value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+For program images, this is the starting address. For device drivers, this is the address of the initialization function. An entry point is optional for DLLs. When no entry point is present, this field must be zero.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="BaseOfCode">
@@ -70,8 +78,8 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the address of the beginning-of-code section relative to the image base when the image is loaded into memory.</summary>
+        <value>The address of the beginning-of-code section relative to the image base.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -96,8 +104,8 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the address of the beginning-of-data section relative to the image base when the image is loaded into memory.</summary>
+        <value>The address of the beginning-of-data section relative to the image base.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -124,7 +132,15 @@
       <Docs>
         <summary>To be added.</summary>
         <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_BASERELOC`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="BoundImportTableDirectory">
@@ -150,7 +166,15 @@
       <Docs>
         <summary>To be added.</summary>
         <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_BOUND_IMPORT`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="CertificateTableDirectory">
@@ -174,9 +198,19 @@
         <ReturnType>System.Reflection.PortableExecutable.DirectoryEntry</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Gets the Certificate Table entry, which points to a table of attribute certificates.</summary>
         <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+These certificates are not loaded into memory as part of the image. As such, the first field of this entry, which is normally an RVA, is a file pointer instead.
+ 
+Represents `IMAGE_DIRECTORY_ENTRY_SECURITY`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="CheckSum">
@@ -200,8 +234,8 @@
         <ReturnType>System.UInt32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the image file checksum.</summary>
+        <value>The image file checksum.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -228,7 +262,15 @@
       <Docs>
         <summary>To be added.</summary>
         <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_COPYRIGHT` or `IMAGE_DIRECTORY_ENTRY_ARCHITECTURE`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="CorHeaderTableDirectory">
@@ -254,7 +296,15 @@
       <Docs>
         <summary>To be added.</summary>
         <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_COM_DESCRIPTOR`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="DebugTableDirectory">
@@ -280,7 +330,15 @@
       <Docs>
         <summary>To be added.</summary>
         <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_DEBUG`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="DelayImportTableDirectory">
@@ -306,7 +364,15 @@
       <Docs>
         <summary>To be added.</summary>
         <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_DELAY_IMPORT`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="DllCharacteristics">
@@ -358,7 +424,15 @@
       <Docs>
         <summary>To be added.</summary>
         <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_EXCEPTION`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="ExportTableDirectory">
@@ -384,7 +458,15 @@
       <Docs>
         <summary>To be added.</summary>
         <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_EXPORT`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="FileAlignment">
@@ -408,9 +490,16 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>Gets the alignment factor (in bytes) that is used to align the raw data of sections in the image file.</summary>
+        <value>A power of 2 between 512 and 64K, inclusive. The default is 512.</value>
+        <remarks><format type="text/markdown">
+  <![CDATA[
+
+## Remarks
+
+If the <xref:System.Reflection.PortableExecutable.PEHeader.SectionAlignment> is less than the architecture's page size, then <xref:System.Reflection.PortableExecutable.PEHeader.FileAlignment> must match <xref:System.Reflection.PortableExecutable.PEHeader.SectionAlignment>.
+
+        ]]></format></remarks>
       </Docs>
     </Member>
     <Member MemberName="GlobalPointerTableDirectory">
@@ -436,7 +525,15 @@
       <Docs>
         <summary>To be added.</summary>
         <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_GLOBALPTR`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="ImageBase">
@@ -460,8 +557,8 @@
         <ReturnType>System.UInt64</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the preferred address of the first byte of the image when it is loaded into memory.</summary>
+        <value>The preferred address, which is a multiple of 64K.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -488,7 +585,15 @@
       <Docs>
         <summary>To be added.</summary>
         <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_IAT`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="ImportTableDirectory">
@@ -514,7 +619,15 @@
       <Docs>
         <summary>To be added.</summary>
         <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_IMPORT`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="LoadConfigTableDirectory">
@@ -540,7 +653,15 @@
       <Docs>
         <summary>To be added.</summary>
         <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_LOAD_CONFIG`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="Magic">
@@ -564,8 +685,8 @@
         <ReturnType>System.Reflection.PortableExecutable.PEMagic</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets a value that identifies the format of the image file.</summary>
+        <value>The format of the image file.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -590,8 +711,8 @@
         <ReturnType>System.UInt16</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the major version number of the image.</summary>
+        <value>The major version number of the image.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -616,8 +737,8 @@
         <ReturnType>System.Byte</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the linker major version number.</summary>
+        <value>The linker major version number.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -642,8 +763,8 @@
         <ReturnType>System.UInt16</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the major version number of the required operating system.</summary>
+        <value>The major version number of the required operating system.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -668,8 +789,8 @@
         <ReturnType>System.UInt16</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the major version number of the subsystem.</summary>
+        <value>The major version number of the subsystem.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -694,8 +815,8 @@
         <ReturnType>System.UInt16</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the minor version number of the image.</summary>
+        <value>The minor version number of the image.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -720,8 +841,8 @@
         <ReturnType>System.Byte</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the linker minor version number.</summary>
+        <value>The linker minor version number.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -746,8 +867,8 @@
         <ReturnType>System.UInt16</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the minor version number of the required operating system.</summary>
+        <value>The minor version number of the required operating system.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -772,8 +893,8 @@
         <ReturnType>System.UInt16</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the minor version number of the subsystem.</summary>
+        <value>The minor version number of the subsystem.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -798,8 +919,8 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the number of data-directory entries in the remainder of the <see cref="T:System.Reflection.PortableExecutable.PEHeader" />. Each describes a location and size.</summary>
+        <value>The number of data-directory entries in the remainder of the <see cref="T:System.Reflection.PortableExecutable.PEHeader" />.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -826,7 +947,15 @@
       <Docs>
         <summary>To be added.</summary>
         <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_RESOURCE`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="SectionAlignment">
@@ -850,8 +979,8 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the alignment (in bytes) of sections when they are loaded into memory.</summary>
+        <value>A number greater than or equal to <see cref="P:System.Reflection.PortableExecutable.PEHeader.FileAlignment" />. The default is the page size for the architecture.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -876,8 +1005,8 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the size of the code (text) section, or the sum of all code sections if there are multiple sections.</summary>
+        <value>the size of the code (text) section, or the sum of all code sections if there are multiple sections.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -902,8 +1031,8 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the combined size of an MS DOS stub, PE header, and section headers rounded up to a multiple of FileAlignment.</summary>
+        <value>The combined size of an MS DOS stub, PE header, and section headers rounded up to a multiple of FileAlignment.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -928,8 +1057,8 @@
         <ReturnType>System.UInt64</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the size of the local heap space to commit.</summary>
+        <value>the size of the local heap space to commit.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -954,8 +1083,8 @@
         <ReturnType>System.UInt64</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the size of the local heap space to reserve. Only <see cref="P:System.Reflection.PortableExecutable.PEHeader.SizeOfHeapCommit" /> is committed; the rest is made available one page at a time until the reserve size is reached.</summary>
+        <value>The size of the local heap space to reserve. </value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -980,8 +1109,8 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the size (in bytes) of the image, including all headers, as the image is loaded in memory.</summary>
+        <value>The size (in bytes) of the image, which is a multiple of <see cref="P:System.Reflection.PortableExecutable.PEHeader.SectionAlignment" />.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -1006,7 +1135,7 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Gets the size of the initialized data section, or the sum of all such sections if there are multiple data sections.</summary>
         <value>To be added.</value>
         <remarks>To be added.</remarks>
       </Docs>
@@ -1032,8 +1161,8 @@
         <ReturnType>System.UInt64</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the size of the stack to commit.</summary>
+        <value>The size of the stack to commit.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -1058,8 +1187,8 @@
         <ReturnType>System.UInt64</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the size of the stack to reserve. Only <see cref="P:System.Reflection.PortableExecutable.PEHeader.SizeOfStackCommit" /> is committed; the rest is made available one page at a time until the reserve size is reached.</summary>
+        <value>The size of the stack to reserve.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -1084,8 +1213,8 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the size of the uninitialized data section (BSS), or the sum of all such sections if there are multiple BSS sections.</summary>
+        <value>The size of the uninitialized data section (BSS) or the sum of all such sections.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -1110,8 +1239,8 @@
         <ReturnType>System.Reflection.PortableExecutable.Subsystem</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the name of the subsystem that is required to run this image.</summary>
+        <value>the name of the subsystem that is required to run this image.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -1138,7 +1267,15 @@
       <Docs>
         <summary>To be added.</summary>
         <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Represents `IMAGE_DIRECTORY_ENTRY_TLS`.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
   </Members>
diff --git a/xml/System.Reflection.PortableExecutable/PEHeaderBuilder.xml b/xml/System.Reflection.PortableExecutable/PEHeaderBuilder.xml
index cb0ef1953f6..812500bf86c 100644
--- a/xml/System.Reflection.PortableExecutable/PEHeaderBuilder.xml
+++ b/xml/System.Reflection.PortableExecutable/PEHeaderBuilder.xml
@@ -17,7 +17,7 @@
   </Base>
   <Interfaces />
   <Docs>
-    <summary>To be added.</summary>
+    <summary>Defines the header for a portable executable (PE) file.</summary>
     <remarks>To be added.</remarks>
   </Docs>
   <Members>
@@ -56,27 +56,35 @@
         <Parameter Name="sizeOfHeapCommit" Type="System.UInt64" Index="18" FrameworkAlternate="netcore-1.1;netcore-2.0;netcore-2.1;netcore-2.2;netcore-3.0" />
       </Parameters>
       <Docs>
-        <param name="machine">To be added.</param>
-        <param name="sectionAlignment">To be added.</param>
-        <param name="fileAlignment">To be added.</param>
-        <param name="imageBase">To be added.</param>
-        <param name="majorLinkerVersion">To be added.</param>
-        <param name="minorLinkerVersion">To be added.</param>
-        <param name="majorOperatingSystemVersion">To be added.</param>
-        <param name="minorOperatingSystemVersion">To be added.</param>
-        <param name="majorImageVersion">To be added.</param>
-        <param name="minorImageVersion">To be added.</param>
-        <param name="majorSubsystemVersion">To be added.</param>
-        <param name="minorSubsystemVersion">To be added.</param>
-        <param name="subsystem">To be added.</param>
-        <param name="dllCharacteristics">To be added.</param>
-        <param name="imageCharacteristics">To be added.</param>
-        <param name="sizeOfStackReserve">To be added.</param>
-        <param name="sizeOfStackCommit">To be added.</param>
-        <param name="sizeOfHeapReserve">To be added.</param>
-        <param name="sizeOfHeapCommit">To be added.</param>
-        <summary>To be added.</summary>
+        <param name="machine">The target machine's CPU architecture.</param>
+        <param name="sectionAlignment">The alignment (in bytes) of sections when they are loaded into memory. It must be greater than or equal to <paramref name="fileAlignment" />. The default is the page size for the architecture.</param>
+        <param name="fileAlignment">The alignment factor (in bytes) that is used to align the raw data of sections in the image file. The value should be a power of 2 between 512 and 64K, inclusive. The default is 512. If the <paramref name="sectionAlignment" /> is less than the architecture's page size, then <paramref name="fileAlignment" /> must match <paramref name="sectionAlignment" />.</param>
+        <param name="imageBase">The preferred address of the first byte of image when loaded into memory; must be a multiple of 64K.</param>
+        <param name="majorLinkerVersion">The linker major version number.</param>
+        <param name="minorLinkerVersion">The linker minor version number.</param>
+        <param name="majorOperatingSystemVersion">The major version number of the required operating system.</param>
+        <param name="minorOperatingSystemVersion">The minor version number of the required operating system.</param>
+        <param name="majorImageVersion">The major version number of the image.</param>
+        <param name="minorImageVersion">The minor version number of the image.</param>
+        <param name="majorSubsystemVersion">The major version number of the subsystem.</param>
+        <param name="minorSubsystemVersion">The minor version number of the subsystem.</param>
+        <param name="subsystem">The subsystem required to run the image.</param>
+        <param name="dllCharacteristics">An object describing the characteristics of the dynamic link library.</param>
+        <param name="imageCharacteristics">An object describing the characteristics of the image.</param>
+        <param name="sizeOfStackReserve">The size of the stack to reserve. Only <paramref name="sizeOfStackCommit"/> is committed; the rest is made available one page at a time until the reserve size is reached.</param>
+        <param name="sizeOfStackCommit">The size of the stack to commit.</param>
+        <param name="sizeOfHeapReserve">The size of the local heap space to reserve. Only <paramref name="sizeOfHeapCommit"/> is committed; the rest is made available one page at a time until the reserve size is reached.</param>
+        <param name="sizeOfHeapCommit">The size of the local heap space to commit.</param>
+        <summary>Initializes a new instance of the <see cref="T:System.Reflection.PortableExecutable.PEHeader" /> class.</summary>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="fileAlignment" /> is not power of 2 between 512 and 64K.
+-or-
+
+<paramref name="sectionAlignment" /> not power of 2.
+
+-or-
+
+<paramref name="sectionAlignment" /> is less than <paramref name="fileAlignment" />.</exception>
       </Docs>
     </Member>
     <Member MemberName="CreateExecutableHeader">
@@ -99,8 +107,8 @@
       </ReturnValue>
       <Parameters />
       <Docs>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <summary>Creates an executable header.</summary>
+        <returns>A <see cref="T:System.Reflection.PortableExecutable.PEHeaderBuilder" /> instance representing the executable header.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -124,8 +132,8 @@
       </ReturnValue>
       <Parameters />
       <Docs>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <summary>Creates a library header.</summary>
+        <returns>A <see cref="T:System.Reflection.PortableExecutable.PEHeaderBuilder" /> instance representing the library header.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -148,8 +156,8 @@
         <ReturnType>System.Reflection.PortableExecutable.DllCharacteristics</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Returns the dynamic linker library characteristics.</summary>
+        <value>An object that describes the dynamic linker library characteristics.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -172,7 +180,7 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>The alignment factor (in bytes) that is used to align the raw data of sections in the image file. The value should be a power of 2 between 512 and 64K, inclusive. The default is 512. If the section alignment is less than the architecture's page size, then file alignment must match the section alignment.</summary>
         <value>To be added.</value>
         <remarks>To be added.</remarks>
       </Docs>
@@ -196,8 +204,8 @@
         <ReturnType>System.UInt64</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>The preferred address of the first byte of image when loaded into memory; must be a multiple of 64K.</summary>
+        <value>A number representing the preferred address of the first byte of image when loaded into memory.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -220,8 +228,8 @@
         <ReturnType>System.Reflection.PortableExecutable.Characteristics</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Returns the image characteristics.</summary>
+        <value>An object representing the image characteristics.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -244,8 +252,8 @@
         <ReturnType>System.Reflection.PortableExecutable.Machine</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>The target machine's CPU architecture.</summary>
+        <value>One of the enumeration values representing the different CPU architectures.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -268,8 +276,8 @@
         <ReturnType>System.UInt16</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>The major version number of the image.</summary>
+        <value>A number the size of a <see cref="T:System.UInt16" /> representing the the major version number of the image.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -292,8 +300,8 @@
         <ReturnType>System.Byte</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>The linker major version number.</summary>
+        <value>A number the size of a <see cref="T:System.Byte" /> representing the linker major version number.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -316,8 +324,8 @@
         <ReturnType>System.UInt16</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>The major version number of the required operating system.</summary>
+        <value>A number the size of a <see cref="T:System.UInt16" /> representing the major version number of the required operating system.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -340,8 +348,8 @@
         <ReturnType>System.UInt16</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>The major version number of the subsystem.</summary>
+        <value>A number the size of a <see cref="T:System.UInt16" /> representing the major version number of the subsystem.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -364,8 +372,8 @@
         <ReturnType>System.UInt16</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>The minor version number of the image.</summary>
+        <value>A number the size of a <see cref="T:System.UInt16" /> representing the minor version number of the image.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -388,8 +396,8 @@
         <ReturnType>System.Byte</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>The linker minor version number.</summary>
+        <value>A number the size of a <see cref="T:System.Byte" /> representing the linker minor version number.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -412,8 +420,8 @@
         <ReturnType>System.UInt16</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>The minor version number of the required operating system.</summary>
+        <value>A number the size of a <see cref="T:System.UInt16" /> representing the minor version number of the required operating system.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -436,8 +444,8 @@
         <ReturnType>System.UInt16</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>The minor version number of the subsystem.</summary>
+        <value>A number the size of a <see cref="T:System.UInt16" /> representing the minor version number of the subsystem.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -460,8 +468,8 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>The alignment (in bytes) of sections when they are loaded into memory.</summary>
+        <value>A number representing the alignment (in bytes) of sections when they are loaded into memory. It must be greater than or equal to the file alignment. The default is the page size for the architecture.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -484,8 +492,8 @@
         <ReturnType>System.UInt64</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>The size of the local heap space to commit.</summary>
+        <value>A number representing the size of the local heap space to commit.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -508,8 +516,8 @@
         <ReturnType>System.UInt64</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>The size of the local heap space to reserve. Only <see cref="P:System.Reflection.PortableExecutable.PEHeaderBuilder.SizeOfHeapCommit" /> is committed; the rest is made available one page at a time until the reserve size is reached.</summary>
+        <value>A number representing the size of the local heap space to reserve.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -532,8 +540,8 @@
         <ReturnType>System.UInt64</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>The size of the stack to commit.</summary>
+        <value>A number representing the size of the stack to commit.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -556,8 +564,8 @@
         <ReturnType>System.UInt64</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>The size of the stack to reserve. Only <see cref="P:System.Reflection.PortableExecutable.PEHeaderBuilder.SizeOfStackCommit" /> is committed; the rest is made available one page at a time until the reserve size is reached.</summary>
+        <value>A number representing the size of the stack to reserve.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -580,8 +588,8 @@
         <ReturnType>System.Reflection.PortableExecutable.Subsystem</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>The subsystem that is required to run this image.</summary>
+        <value>A <see cref="T:System.Reflection.PortableExecutable.Subsystem" /> instance.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
diff --git a/xml/System.Reflection.PortableExecutable/PEHeaders.xml b/xml/System.Reflection.PortableExecutable/PEHeaders.xml
index 2aea8949902..416e1b8e17b 100644
--- a/xml/System.Reflection.PortableExecutable/PEHeaders.xml
+++ b/xml/System.Reflection.PortableExecutable/PEHeaders.xml
@@ -19,7 +19,7 @@
   </Base>
   <Interfaces />
   <Docs>
-    <summary>To be added.</summary>
+    <summary>Defines a type that reads PE (Portable Executable) and COFF (Common Object File Format) headers from a stream.</summary>
     <remarks>To be added.</remarks>
   </Docs>
   <Members>
@@ -44,9 +44,13 @@
         <Parameter Name="peStream" Type="System.IO.Stream" />
       </Parameters>
       <Docs>
-        <param name="peStream">To be added.</param>
-        <summary>To be added.</summary>
+        <param name="peStream">A stream containing the PE image starting at the stream's current position and ending at the end of the stream.</param>
+        <summary>Instantiates a new instance of the <see cref="T:System.Reflection.PortableExecutable.PEHeaders" /> class that reads the PE headers from the current location in the specified stream.</summary>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.BadImageFormatException">The data read from the stream has an invalid format.</exception>
+        <exception cref="T:System.IO.IOException">Error reading from the stream.</exception>
+        <exception cref="T:System.ArgumentException">The stream does not support seek operations.</exception>
+        <exception cref="T:System.ArgumentNullException"><paramref name="peStream" /> is <see langword="null" />.</exception>
       </Docs>
     </Member>
     <Member MemberName=".ctor">
@@ -71,10 +75,15 @@
         <Parameter Name="size" Type="System.Int32" />
       </Parameters>
       <Docs>
-        <param name="peStream">To be added.</param>
-        <param name="size">To be added.</param>
-        <summary>To be added.</summary>
+        <param name="peStream">A stream containing PE image of the given size starting at its current position.</param>
+        <param name="size">The size of the PE image.</param>
+        <summary>Instantiates a new instance of the <see cref="T:System.Reflection.PortableExecutable.PEHeaders" /> class that reads the PE headers from a stream that represents a PE image of a specified size.</summary>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.BadImageFormatException">The data read from the stream has an invalid format.</exception>
+        <exception cref="T:System.IO.IOException">Error reading from the stream.</exception>
+        <exception cref="T:System.ArgumentException">The stream does not support seek operations.</exception>
+        <exception cref="T:System.ArgumentNullException"><paramref name="peStream" /> is <see langword="null" />.</exception>
+        <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="size" /> is negative or extends past the end of the stream.</exception>
       </Docs>
     </Member>
     <Member MemberName=".ctor">
@@ -98,11 +107,16 @@
         <Parameter Name="isLoadedImage" Type="System.Boolean" Index="2" FrameworkAlternate="netcore-1.1;netcore-2.0;netcore-2.1;netcore-2.2;netcore-3.0" />
       </Parameters>
       <Docs>
-        <param name="peStream">To be added.</param>
-        <param name="size">To be added.</param>
-        <param name="isLoadedImage">To be added.</param>
-        <summary>To be added.</summary>
+        <param name="peStream">The stream containing PE image of the given size starting at its current position.</param>
+        <param name="size">The size of the PE image.</param>
+        <param name="isLoadedImage"><see langword="true" /> if the PE image has been loaded into memory by the OS loader; otherwise, <see langword="false" />.</param>
+        <summary>Instantiates a new instance of the <see cref="T:System.Reflection.PortableExecutable.PEHeaders" /> class that reads the PE headers from a stream that represents a PE image of a specified size and indicates whether the PE image has been loaded into memory.</summary>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.BadImageFormatException">The data read from the stream has invalid format.</exception>
+        <exception cref="T:System.IO.IOException">Error reading from the stream.</exception>
+        <exception cref="T:System.ArgumentException">The stream does not support seek operations.</exception>
+        <exception cref="T:System.ArgumentNullException"><paramref name="peStream" /> is <see langword="null" />.</exception>
+        <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="size" /> is negative or extends past the end of the stream.</exception>
       </Docs>
     </Member>
     <Member MemberName="CoffHeader">
@@ -126,8 +140,8 @@
         <ReturnType>System.Reflection.PortableExecutable.CoffHeader</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the COFF header of the image.</summary>
+        <value>The COFF header of the image.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -152,8 +166,8 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the byte offset from the start of the PE image to the start of the COFF header.</summary>
+        <value>The byte offset from the start of the PE image to the start of the COFF header.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -178,8 +192,8 @@
         <ReturnType>System.Reflection.PortableExecutable.CorHeader</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the COR header.</summary>
+        <value>The COR header, or <see langword="null" /> if the image does not have one.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -204,8 +218,8 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the byte offset from the start of the image to the COR header.</summary>
+        <value>The byte offset from the start of the image to the COR header, or -1 if the image does not have a COR header.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -233,9 +247,9 @@
         <Parameter Name="relativeVirtualAddress" Type="System.Int32" />
       </Parameters>
       <Docs>
-        <param name="relativeVirtualAddress">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="relativeVirtualAddress">The relative virtual address to search for.</param>
+        <summary>Searches sections of the PE image for the section that contains the specified Relative Virtual Address.</summary>
+        <returns>The index of the section that contains <paramref name="relativeVirtualAddress" />, or -1 if there the search is unsuccessful.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -260,8 +274,8 @@
         <ReturnType>System.Boolean</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets a value that indicates whether the image is Coff only.</summary>
+        <value><see langword="true" /> if the image is Coff only; otherwise, <see langword="false" />.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -286,8 +300,8 @@
         <ReturnType>System.Boolean</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets a value that indicates whether the image represents a Windows console application.</summary>
+        <value><see langword="true" /> if the image is a Windows console applications; otherwise, <see langword="false" />.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -312,8 +326,8 @@
         <ReturnType>System.Boolean</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets a value that indicates whether the image represents a dynamic link library.</summary>
+        <value><see langword="true" /> if the image is a DLL; otherwise, <see langword="false" />.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -338,8 +352,8 @@
         <ReturnType>System.Boolean</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets a value that indicates whether the image represents an executable.</summary>
+        <value><see langword="true" /> if the image is an executable; otherwise, <see langword="false" />.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -364,8 +378,8 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the size of the CLI metadata.</summary>
+        <value>the size of the CLI metadata, or 0 if the image does not contain metadata.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -390,8 +404,8 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the offset (in bytes) from the start of the PE image to the start of the CLI metadata.</summary>
+        <value>The offset (in bytes) from the start of the PE image to the start of the CLI metadata, or -1 if the image does not contain metadata.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -416,8 +430,8 @@
         <ReturnType>System.Reflection.PortableExecutable.PEHeader</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the image's PE header.</summary>
+        <value>The image's PE header, or <see langword="null" /> if the image is COFF only.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -442,8 +456,8 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the byte offset of the header from the start of the image.</summary>
+        <value>The byte offset of the header from the start of the image.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -468,8 +482,8 @@
         <ReturnType>System.Collections.Immutable.ImmutableArray&lt;System.Reflection.PortableExecutable.SectionHeader&gt;</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the PE section headers.</summary>
+        <value>An array containing the PE section headers.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -498,10 +512,10 @@
         <Parameter Name="offset" Type="System.Int32" RefType="out" />
       </Parameters>
       <Docs>
-        <param name="directory">To be added.</param>
-        <param name="offset">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="directory">The PE directory entry.</param>
+        <param name="offset">When the method returns, contains the offset from the start of the image to the given directory data.</param>
+        <summary>Gets the offset (in bytes) from the start of the image to the given directory data.</summary>
+        <returns><see langword="true" /> if the directory data is found; <see langword="false" /> otherwise.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
diff --git a/xml/System.Reflection.PortableExecutable/PEMemoryBlock.xml b/xml/System.Reflection.PortableExecutable/PEMemoryBlock.xml
index fc2d2766034..14be5983d2c 100644
--- a/xml/System.Reflection.PortableExecutable/PEMemoryBlock.xml
+++ b/xml/System.Reflection.PortableExecutable/PEMemoryBlock.xml
@@ -50,8 +50,8 @@
       </ReturnValue>
       <Parameters />
       <Docs>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <summary>Reads the contents of the entire block into an array.</summary>
+        <returns>An immutable byte array.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -78,11 +78,12 @@
         <Parameter Name="length" Type="System.Int32" Index="1" FrameworkAlternate="netcore-1.1;netcore-2.0;netcore-2.1;netcore-2.2;netcore-3.0" />
       </Parameters>
       <Docs>
-        <param name="start">To be added.</param>
-        <param name="length">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="start">The starting position in the block.</param>
+        <param name="length">The number of bytes to read.</param>
+        <summary>Reads the contents of a part of the block into an array.</summary>
+        <returns>An immutable array of bytes.</returns>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.ArgumentOutOfRangeException">The specified range is not contained within the block.</exception>
       </Docs>
     </Member>
     <Member MemberName="GetReader">
@@ -105,8 +106,8 @@
       </ReturnValue>
       <Parameters />
       <Docs>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <summary>Creates a <see cref="T:System.Reflection.Metadata.BlobReader" /> for a blob spanning the entire block.</summary>
+        <returns>A reader for a blob spanning the entire block.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -133,11 +134,12 @@
         <Parameter Name="length" Type="System.Int32" Index="1" FrameworkAlternate="netcore-1.1;netcore-2.0;netcore-2.1;netcore-2.2;netcore-3.0" />
       </Parameters>
       <Docs>
-        <param name="start">To be added.</param>
-        <param name="length">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="start">The starting position in the block.</param>
+        <param name="length">The number of bytes in the portion of the block.</param>
+        <summary>Creates a <see cref="T:System.Reflection.Metadata.BlobReader" /> for a blob spanning a part of the block.</summary>
+        <returns>A reader for a blob spanning a portion of the block.</returns>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.ArgumentOutOfRangeException">The specified range is not contained within the block.</exception>
       </Docs>
     </Member>
     <Member MemberName="Length">
@@ -161,8 +163,8 @@
         <ReturnType>System.Int32</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the length of the block.</summary>
+        <value>The length of the block.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -186,8 +188,8 @@
         <ReturnType>System.Byte*</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets a pointer to the first byte of the block.</summary>
+        <value>A pointer to the first byte of the block.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
diff --git a/xml/System.Reflection.PortableExecutable/PEReader.xml b/xml/System.Reflection.PortableExecutable/PEReader.xml
index aa02b829396..70143dde642 100644
--- a/xml/System.Reflection.PortableExecutable/PEReader.xml
+++ b/xml/System.Reflection.PortableExecutable/PEReader.xml
@@ -23,8 +23,16 @@
     </Interface>
   </Interfaces>
   <Docs>
-    <summary>To be added.</summary>
-    <remarks>To be added.</remarks>
+    <summary>Provides a reader for Portable Executable format (PE) files.</summary>
+    <remarks>
+      <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+The implementation is thread-safe. That is, multiple threads can read data from the reader in parallel. Disposal of the reader is not thread-safe (see <xref:System.Reflection.PortableExecutable.PEReader.Dispose>).
+
+          ]]></format>
+    </remarks>
   </Docs>
   <Members>
     <Member MemberName=".ctor">
@@ -48,9 +56,18 @@
         <Parameter Name="peImage" Type="System.Collections.Immutable.ImmutableArray&lt;System.Byte&gt;" />
       </Parameters>
       <Docs>
-        <param name="peImage">To be added.</param>
-        <summary>To be added.</summary>
-        <remarks>To be added.</remarks>
+        <param name="peImage">An immutable array of bytes representing the PE image.</param>
+        <summary>Creates a Portable Executable reader over a PE image stored in a byte array.</summary>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+The content of the image is not read during the construction of the <xref:System.Reflection.PortableExecutable.PEReader>
+
+          ]]></format>
+        </remarks>
+        <exception cref="T:System.ArgumentNullException"><paramref name="peImage" /> is <see langword="null" />.</exception>
       </Docs>
     </Member>
     <Member MemberName=".ctor">
@@ -74,9 +91,18 @@
         <Parameter Name="peStream" Type="System.IO.Stream" />
       </Parameters>
       <Docs>
-        <param name="peStream">To be added.</param>
-        <summary>To be added.</summary>
-        <remarks>To be added.</remarks>
+        <param name="peStream">PE image stream.</param>
+        <summary>Creates a Portable Executable reader over a PE image stored in a stream.</summary>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Ownership of the stream is transferred to the <xref:System.Reflection.PortableExecutable.PEReader> upon successful validation of constructor arguments. It will be disposed by the <xref:System.Reflection.PortableExecutable.PEReader> and the caller must not manipulate it.
+
+          ]]></format>
+        </remarks>
+        <exception cref="T:System.ArgumentNullException"><paramref name="peStream" /> is <see langword="null" />.</exception>
       </Docs>
     </Member>
     <Member MemberName=".ctor">
@@ -100,10 +126,23 @@
         <Parameter Name="size" Type="System.Int32" />
       </Parameters>
       <Docs>
-        <param name="peImage">To be added.</param>
-        <param name="size">To be added.</param>
-        <summary>To be added.</summary>
-        <remarks>To be added.</remarks>
+        <param name="peImage">A pointer to the start of the PE image.</param>
+        <param name="size">The size of the PE image.</param>
+        <summary>Creates a Portable Executable reader over a PE image stored in memory.</summary>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+The memory is owned by the caller and not released on disposal of the <xref:System.Reflection.PortableExecutable.PEReader>. The caller is responsible for keeping the memory alive and unmodified throughout the lifetime of the <xref:System.Reflection.PortableExecutable.PEReader>.
+
+
+The content of the image is not read during the construction of the <xref:System.Reflection.PortableExecutable.PEReader>
+
+          ]]></format>
+        </remarks>
+        <exception cref="T:System.ArgumentNullException"><paramref name="peImage" /> is <see cref="F:System.IntPtr.Zero" />.</exception>
+        <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="size" /> is negative.</exception>
       </Docs>
     </Member>
     <Member MemberName=".ctor">
@@ -128,10 +167,26 @@
         <Parameter Name="options" Type="System.Reflection.PortableExecutable.PEStreamOptions" />
       </Parameters>
       <Docs>
-        <param name="peStream">To be added.</param>
-        <param name="options">To be added.</param>
-        <summary>To be added.</summary>
-        <remarks>To be added.</remarks>
+        <param name="peStream">A PE image stream.</param>
+        <param name="options">Options specifying how sections of the PE image are read from the stream.</param>
+        <summary>Creates a Portable Executable reader over a PE image stored in a stream beginning at its current position and ending at the end of the stream.</summary>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+ 
+Unless <xref:System.Reflection.PortableExecutable.PEStreamOptions.LeaveOpen?displayProperty=nameWithType> is specified, ownership of the stream is transferred to the <xref:System.Reflection.PortableExecutable.PEReader> upon successful argument validation. It will be disposed by the <xref:System.Reflection.PortableExecutable.PEReader> and the caller must not manipulate it.
+ 
+Unless <xref:System.Reflection.PortableExecutable.PEStreamOptions.PrefetchMetadata?displayProperty=nameWithType> or <xref:System.Reflection.PortableExecutable.PEStreamOptions.PrefetchEntireImage?displayProperty=nameWithType> is specified, no data is read from the stream during the construction of the <xref:System.Reflection.PortableExecutable.PEReader>. Furthermore, the stream must not be manipulated by caller while the <xref:System.Reflection.PortableExecutable.PEReader> is alive and undisposed.
+ 
+If `options` includes <xref:System.Reflection.PortableExecutable.PEStreamOptions.PrefetchMetadata?displayProperty=nameWithType> or <xref:System.Reflection.PortableExecutable.PEStreamOptions.PrefetchEntireImage?displayProperty=nameWithType>, the <xref:System.Reflection.PortableExecutable.PEReader> will have read all of the data requested during construction. As such, if <xref:System.Reflection.PortableExecutable.PEStreamOptions.LeaveOpen?displayProperty=nameWithType> is also specified, the caller retains full ownership of the stream and is assured that it will not be manipulated by the <xref:System.Reflection.PortableExecutable.PEReader> after construction.
+
+          ]]></format>
+        </remarks>
+        <exception cref="T:System.ArgumentNullException"><paramref name="peStream" /> is <see langword="null" />.</exception>
+        <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="options" /> has an invalid value.</exception>
+        <exception cref="T:System.IO.IOException">Error reading from the stream (only when prefetching data).</exception>
+        <exception cref="T:System.BadImageFormatException"><see cref="F:System.Reflection.PortableExecutable.PEStreamOptions.PrefetchMetadata" /> is specified, and the PE headers of the image are invalid.</exception>
       </Docs>
     </Member>
     <Member MemberName=".ctor">
@@ -154,11 +209,24 @@
         <Parameter Name="isLoadedImage" Type="System.Boolean" Index="2" FrameworkAlternate="netcore-1.1;netcore-2.0;netcore-2.1;netcore-2.2;netcore-3.0" />
       </Parameters>
       <Docs>
-        <param name="peImage">To be added.</param>
-        <param name="size">To be added.</param>
-        <param name="isLoadedImage">To be added.</param>
-        <summary>To be added.</summary>
-        <remarks>To be added.</remarks>
+        <param name="peImage">A pointer to the start of the PE image.</param>
+        <param name="size">The size of the PE image.</param>
+        <param name="isLoadedImage"><see langword="true" /> if the PE image has been loaded into memory by the OS loader; otherwise, <see langword="false" />.</param>
+        <summary>Creates a Portable Executable reader over a PE image stored in memory. A flag indicates whether the image has already been loaded into memory.</summary>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+The memory is owned by the caller and is not released when the <xref:System.Reflection.PortableExecutable.PEReader> is disposed. The caller is responsible for keeping the memory alive and unmodified throughout the lifetime of the <xref:System.Reflection.PortableExecutable.PEReader>.
+
+
+The content of the image is not read during the construction of the <xref:System.Reflection.PortableExecutable.PEReader>
+
+          ]]></format>
+        </remarks>
+        <exception cref="T:System.ArgumentNullException"><paramref name="peImage" /> is <see cref="F:System.IntPtr.Zero" />.</exception>
+        <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="size" /> is negative.</exception>
       </Docs>
     </Member>
     <Member MemberName=".ctor">
@@ -184,11 +252,26 @@
         <Parameter Name="size" Type="System.Int32" />
       </Parameters>
       <Docs>
-        <param name="peStream">To be added.</param>
-        <param name="options">To be added.</param>
-        <param name="size">To be added.</param>
-        <summary>To be added.</summary>
-        <remarks>To be added.</remarks>
+        <param name="peStream">A PE image stream.</param>
+        <param name="options">Options specifying how sections of the PE image are read from the stream.</param>
+        <param name="size">The PE image size.</param>
+        <summary>Creates a Portable Executable reader over a PE image of the given size beginning at the stream's current position.</summary>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+Unless <xref:System.Reflection.PortableExecutable.PEStreamOptions.LeaveOpen?displayProperty=nameWithType> is specified, ownership of the stream is transferred to the <xref:System.Reflection.PortableExecutable.PEReader> upon successful argument validation. It will be disposed by the <xref:System.Reflection.PortableExecutable.PEReader>, and the caller must not manipulate it.
+ 
+Unless <xref:System.Reflection.PortableExecutable.PEStreamOptions.PrefetchMetadata?displayProperty=nameWithType> or <xref:System.Reflection.PortableExecutable.PEStreamOptions.PrefetchEntireImage?displayProperty=nameWithType> is specified, no data is read from the stream during the construction of the <xref:System.Reflection.PortableExecutable.PEReader>. Furthermore, the stream must not be manipulated by the caller while the <xref:System.Reflection.PortableExecutable.PEReader> is alive and undisposed.
+ 
+If `options` includes the <xref:System.Reflection.PortableExecutable.PEStreamOptions.PrefetchMetadata?displayProperty=nameWithType> or <xref:System.Reflection.PortableExecutable.PEStreamOptions.PrefetchEntireImage?displayProperty=nameWithType> values, the <xref:System.Reflection.PortableExecutable.PEReader> will have read all of the data requested during construction. As such, if <xref:System.Reflection.PortableExecutable.PEStreamOptions.LeaveOpen?displayProperty=nameWithType> is also specified, the caller retains full ownership of the stream and is assured that it will not be manipulated by the <xref:System.Reflection.PortableExecutable.PEReader> after construction.
+
+          ]]></format>
+        </remarks>
+        <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="size" /> is negative or extends past the end of the stream.</exception>
+        <exception cref="T:System.IO.IOException">Error reading from the stream (only when prefetching data).</exception>
+        <exception cref="T:System.BadImageFormatException"><see cref="F:System.Reflection.PortableExecutable.PEStreamOptions.PrefetchMetadata" /> is specified, and the PE headers of the image are invalid.</exception>
       </Docs>
     </Member>
     <Member MemberName="Dispose">
@@ -216,8 +299,18 @@
       </ReturnValue>
       <Parameters />
       <Docs>
-        <summary>To be added.</summary>
-        <remarks>To be added.</remarks>
+        <summary>Disposes all memory allocated by the reader.</summary>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+> [!IMPORTANT]
+> <xref:System.Reflection.PortableExecutable.PEReader.Dispose>  can be called multiple times, but not in parallel.
+> It is not safe to call <xref:System.Reflection.PortableExecutable.PEReader.Dispose> in parallel with any other operation on the <xref:System.Reflection.PortableExecutable.PEReader> or when reading from <xref:System.Reflection.PortableExecutable.PEMemoryBlock>s retrieved from the reader.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="GetEntireImage">
@@ -242,9 +335,16 @@
       </ReturnValue>
       <Parameters />
       <Docs>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
-        <remarks>To be added.</remarks>
+        <summary>Gets a <see cref="T:System.Reflection.PortableExecutable.PEMemoryBlock" /> object containing the entire PE image.</summary>
+        <returns>A memory block that contains the entire PE image.</returns>
+        <remarks>  
+          <format type="text/markdown"><![CDATA[  
+
+You can retrieve the value of the <xref:System.Reflection.PortableExecutable.PEReader.IsEntireImageAvailable> property to determine whether the <xref:System.Reflection.PortableExecutable.PEReader> makes the entire image available.
+
+         ]]></format>
+         </remarks>
+        <exception cref="T:System.InvalidOperationException">The entire PE image is not available.</exception>
       </Docs>
     </Member>
     <Member MemberName="GetMetadata">
@@ -269,9 +369,12 @@
       </ReturnValue>
       <Parameters />
       <Docs>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <summary>Loads a PE section that contains CLI metadata.</summary>
+        <returns>A memory block that contains the CLI metadata.</returns>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.InvalidOperationException">The PE image doesn't contain metadata (<see cref="P:System.Reflection.PortableExecutable.PEReader.HasMetadata" /> returns <see langword="false" />).</exception>
+        <exception cref="T:System.BadImageFormatException">The PE headers contain invalid data.</exception>
+        <exception cref="T:System.IO.IOException">IO error while reading from the underlying stream.</exception>
       </Docs>
     </Member>
     <Member MemberName="GetSectionData">
@@ -298,10 +401,14 @@
         <Parameter Name="relativeVirtualAddress" Type="System.Int32" />
       </Parameters>
       <Docs>
-        <param name="relativeVirtualAddress">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="relativeVirtualAddress">The Relative Virtual Address of the data to read.</param>
+        <summary>Loads the PE section that contains the specified relative virtual address into memory and returns a memory block that starts at that address and ends at the end of the containing section.</summary>
+        <returns>A memory block that starats at <paramref name="relativeVirtualAddress" /> and ends at the end of the containing section, or an empty block if <paramref name="relativeVirtualAddress" /> doesn't represent a location in any of the PE sections of this PE image.</returns>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.BadImageFormatException">The PE headers contain invalid data.</exception>
+        <exception cref="T:System.IO.IOException">An IO error occurred while reading from the underlying stream.</exception>
+        <exception cref="T:System.InvalidOperationException">The PE image is not available.</exception>
+        <exception cref="T:System.ArgumentOutOfRangeException"><paramref name="relativeVirtualAddress" /> is negative.</exception>
       </Docs>
     </Member>
     <Member MemberName="GetSectionData">
@@ -326,10 +433,12 @@
         <Parameter Name="sectionName" Type="System.String" Index="0" FrameworkAlternate="netcore-1.1;netcore-2.0;netcore-2.1;netcore-2.2;netcore-3.0" />
       </Parameters>
       <Docs>
-        <param name="sectionName">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="sectionName">The name of the section.</param>
+        <summary>Loads the PE section with the specified name into memory and returns a memory block that spans the section.</summary>
+        <returns>A memory block that spans the section, or an empty block if no section of the given <paramref name="sectionName" /> exists in this PE image.</returns>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.ArgumentNullException"><paramref name="sectionName" /> is <see langword="null" />.</exception>
+        <exception cref="T:System.InvalidOperationException">The PE image is not available.</exception>
       </Docs>
     </Member>
     <Member MemberName="HasMetadata">
@@ -353,9 +462,11 @@
         <ReturnType>System.Boolean</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets a value that indicates if the PE image contains CLI metadata.</summary>
+        <value><see langword="true" /> if the PE image contains CLI metadata; otherwise, <see langword="false" />.</value>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.BadImageFormatException">The PE headers contain invalid data.</exception>
+        <exception cref="T:System.IO.IOException">Error reading from the underlying stream.</exception>
       </Docs>
     </Member>
     <Member MemberName="IsEntireImageAvailable">
@@ -379,9 +490,17 @@
         <ReturnType>System.Boolean</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>Gets a value that indicates if the reader can access the entire PE image.</summary>
+        <value><see langword="true" /> if the reader can access the entire PE image; otherwise, <see langword="false" />.</value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+The property returns `false` if the <xref:System.Reflection.PortableExecutable.PEReader> is constructed from a stream and only part of it is prefetched into memory.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="IsLoadedImage">
@@ -403,8 +522,8 @@
         <ReturnType>System.Boolean</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets a value that indicates if the PE image has been loaded into memory by the OS loader.</summary>
+        <value><see langword="true" /> if the PE image has been loaded into memory by the OS loader; otherwise, <see langword="false" />.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -429,9 +548,11 @@
         <ReturnType>System.Reflection.PortableExecutable.PEHeaders</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the PE headers.</summary>
+        <value>The PE headers for this PE image.</value>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.BadImageFormatException">The headers contain invalid data.</exception>
+        <exception cref="T:System.IO.IOException">Error reading from the stream.</exception>
       </Docs>
     </Member>
     <Member MemberName="ReadCodeViewDebugDirectoryData">
@@ -457,10 +578,14 @@
         <Parameter Name="entry" Type="System.Reflection.PortableExecutable.DebugDirectoryEntry" Index="0" FrameworkAlternate="netcore-1.0;netcore-1.1;netcore-2.0;netcore-2.1;netcore-2.2;netcore-3.0" />
       </Parameters>
       <Docs>
-        <param name="entry">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="entry">A Debug Directory entry instance.</param>
+        <summary>Reads the data pointed to by the specified Debug Directory entry and interprets it as CodeView.</summary>
+        <returns>A code view debug directory data instance.</returns>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.ArgumentException"><paramref name="entry" /> is not a CodeView entry.</exception>
+        <exception cref="T:System.BadImageFormatException">Bad format of the data.</exception>
+        <exception cref="T:System.IO.IOException">IO error while reading from the underlying stream.</exception>
+        <exception cref="T:System.InvalidOperationException">The PE image is not available.</exception>
       </Docs>
     </Member>
     <Member MemberName="ReadDebugDirectory">
@@ -484,9 +609,12 @@
       </ReturnValue>
       <Parameters />
       <Docs>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <summary>Reads all Debug Directory table entries.</summary>
+        <returns>An array of Debug Directory table entries.</returns>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.BadImageFormatException">Bad format of the entry.</exception>
+        <exception cref="T:System.IO.IOException">IO error while reading from the underlying stream.</exception>
+        <exception cref="T:System.InvalidOperationException">The PE image is not available.</exception>
       </Docs>
     </Member>
     <Member MemberName="ReadEmbeddedPortablePdbDebugDirectoryData">
@@ -511,10 +639,13 @@
         <Parameter Name="entry" Type="System.Reflection.PortableExecutable.DebugDirectoryEntry" Index="0" FrameworkAlternate="netcore-1.1;netcore-2.0;netcore-2.1;netcore-2.2;netcore-3.0" />
       </Parameters>
       <Docs>
-        <param name="entry">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="entry">The Debug Directory entry whose data is to be read.</param>
+        <summary>Reads the data pointed to by the specified Debug Directory entry and interprets it as an Embedded Portable PDB blob.</summary>
+        <returns>The provider of a metadata reader for reading a Portable PDB image.</returns>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.ArgumentException"><paramref name="entry" /> is not a <see cref="F:System.Reflection.PortableExecutable.DebugDirectoryEntryType.EmbeddedPortablePdb" /> entry.</exception>
+        <exception cref="T:System.BadImageFormatException">Bad format of the data.</exception>
+        <exception cref="T:System.InvalidOperationException">PE image not available.</exception>
       </Docs>
     </Member>
     <Member MemberName="ReadPdbChecksumDebugDirectoryData">
@@ -537,10 +668,14 @@
         <Parameter Name="entry" Type="System.Reflection.PortableExecutable.DebugDirectoryEntry" Index="0" FrameworkAlternate="netcore-2.1;netcore-2.2;netcore-3.0" />
       </Parameters>
       <Docs>
-        <param name="entry">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="entry">The Debug Directory entry whose data is to be read.</param>
+        <summary>Reads the data pointed to by the specified Debug Directory entry and interprets it as a PDB Checksum entry.</summary>
+        <returns>The PDB Checksum entry.</returns>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.ArgumentException"><paramref name="entry" /> is not a PDB Checksum entry.</exception>
+        <exception cref="T:System.BadImageFormatException">Bad format of the data.</exception>
+        <exception cref="T:System.IO.IOException">IO error while reading from the underlying stream.</exception>
+        <exception cref="T:System.InvalidOperationException">The PE image is not available.</exception>
       </Docs>
     </Member>
     <Member MemberName="TryOpenAssociatedPortablePdb">
@@ -568,13 +703,32 @@
         <Parameter Name="pdbPath" Type="System.String" RefType="out" Index="3" FrameworkAlternate="netcore-1.1;netcore-2.0;netcore-2.1;netcore-2.2;netcore-3.0" />
       </Parameters>
       <Docs>
-        <param name="peImagePath">To be added.</param>
-        <param name="pdbFileStreamProvider">To be added.</param>
-        <param name="pdbReaderProvider">To be added.</param>
-        <param name="pdbPath">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
-        <remarks>To be added.</remarks>
+        <param name="peImagePath">The path to the PE image. The path is used to locate the PDB file located in the directory containing the PE file.</param>
+        <param name="pdbFileStreamProvider">If specified, called to open a <see cref="T:System.IO.Stream" /> for a given file path. The provider is expected to either return a readable and seekable <see cref="T:System.IO.Stream" />, or <see langword="null" /> if the target file doesn't exist or should be ignored for some reason. The provider should throw <see cref="T:System.IO.IOException" /> if it fails to open the file due to an unexpected IO error.</param>
+        <param name="pdbReaderProvider">If successful, a new instance of <see cref="T:System.Reflection.Metadata.MetadataReaderProvider" /> to be used to read the Portable PDB,.</param>
+        <param name="pdbPath">If successful and the PDB is found in a file, the path to the file, or <see langword="null" /> if the PDB is embedded in the PE image itself.</param>
+        <summary>Opens a Portable PDB associated with this PE image.</summary>
+        <returns><see langword="true" /> if the PE image has a PDB associated with it and the PDB has been successfully opened; otherwise, <see langword="false" />.</returns>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+This method implements a simple PDB file lookup based on the content of the PE image Debug Directory. A more sophisticated tool might need to follow up with additional lookup on search paths or a symbol server.
+ 
+The method looks the PDB up in the following order:
+
+1) Checks for a matching PDB file of the name found in the CodeView entry in the directory containing the PE file (the directory of `peImagePath`).
+2) Checks for a PDB embedded in the PE image itself.
+ 
+The first PDB that matches the information specified in the Debug Directory is returned.
+
+          ]]></format>
+        </remarks>
+        <exception cref="T:System.ArgumentNullException"><paramref name="peImagePath" /> or <paramref name="pdbFileStreamProvider" /> is <see langword="null" />.</exception>
+        <exception cref="T:System.InvalidOperationException">The stream returned from <paramref name="pdbFileStreamProvider" /> doesn't support read and seek operations.</exception>
+        <exception cref="T:System.BadImageFormatException">No matching PDB file was found due to an error: The PE image or the PDB is invalid.</exception>
+        <exception cref="T:System.IO.IOException">No matching PDB file was found due to an error: An IO error occurred while reading the PE image or the PDB.</exception>
       </Docs>
     </Member>
   </Members>
diff --git a/xml/System.Reflection.PortableExecutable/PEStreamOptions.xml b/xml/System.Reflection.PortableExecutable/PEStreamOptions.xml
index 97f25dced95..d204f2f2cfb 100644
--- a/xml/System.Reflection.PortableExecutable/PEStreamOptions.xml
+++ b/xml/System.Reflection.PortableExecutable/PEStreamOptions.xml
@@ -23,7 +23,7 @@
     </Attribute>
   </Attributes>
   <Docs>
-    <summary>To be added.</summary>
+    <summary>Provides options that specify how sections of a PE image are read from a stream.</summary>
     <remarks>To be added.</remarks>
   </Docs>
   <Members>
@@ -49,7 +49,7 @@
       </ReturnValue>
       <MemberValue>0</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>By default, the stream is disposed when the <see cref="T:System.Reflection.PortableExecutable.PEReader" /> is disposed, and sections of the PE image are read lazily.</summary>
       </Docs>
     </Member>
     <Member MemberName="IsLoadedImage">
@@ -72,7 +72,7 @@
       </ReturnValue>
       <MemberValue>8</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Indicates that the underlying PE image has been loaded into memory by the OS loader.</summary>
       </Docs>
     </Member>
     <Member MemberName="LeaveOpen">
@@ -97,7 +97,7 @@
       </ReturnValue>
       <MemberValue>1</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Keeps the stream open when the <see cref="T:System.Reflection.PortableExecutable.PEReader" /> is disposed.</summary>
       </Docs>
     </Member>
     <Member MemberName="PrefetchEntireImage">
@@ -122,7 +122,7 @@
       </ReturnValue>
       <MemberValue>4</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>Reads the entire image into memory right away. <see cref="T:System.Reflection.PortableExecutable.PEReader" /> closes the stream automatically by the time the constructor returns unless <see cref="F:System.Reflection.PortableExecutable.PEStreamOptions.LeaveOpen" /> is specified.</summary>
       </Docs>
     </Member>
     <Member MemberName="PrefetchMetadata">
@@ -147,7 +147,7 @@
       </ReturnValue>
       <MemberValue>2</MemberValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary><para>Reads the metadata section into memory right away.</para><para>Reading from other sections of the file is not allowed (<see cref="T:System.InvalidOperationException" /> is thrown by the <see cref="T:System.Reflection.PortableExecutable.PEReader" />).</para><para><see cref="T:System.Reflection.PortableExecutable.PEReader" /> closes the stream automatically by the time the constructor returns unless <see cref="F:System.Reflection.PortableExecutable.PEStreamOptions.LeaveOpen" /> is specified. The underlying file may be closed and even deleted after <see cref="T:System.Reflection.PortableExecutable.PEReader" /> is constructed.</para></summary>
       </Docs>
     </Member>
   </Members>