From 7ca53225d2cf80e2d362dbd2c1453b6050c2b7dd Mon Sep 17 00:00:00 2001
From: Scott Schurr <scott@ripple.com>
Date: Mon, 5 Jun 2023 13:42:19 -0700
Subject: [PATCH 1/3] Add comments for NFToken-related invariants

---
 src/ripple/app/tx/impl/InvariantCheck.h | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/ripple/app/tx/impl/InvariantCheck.h b/src/ripple/app/tx/impl/InvariantCheck.h
index c3bb0216426..50c422f938a 100644
--- a/src/ripple/app/tx/impl/InvariantCheck.h
+++ b/src/ripple/app/tx/impl/InvariantCheck.h
@@ -318,6 +318,17 @@ class ValidNewAccountRoot
         beast::Journal const&);
 };
 
+/**
+ * @brief Invariant: Validates several invariants for NFToken pages.
+ *
+ * The following checks are made:
+ *  - The page is correctly associated with the owner.
+ *  - The page is correctly ordered between the next and previous links.
+ *  - The page contains a valid number of NFTokens.
+ *  - The NFTokens on this page do not belong on a lower or higher page.
+ *  - The NFTokens are correctly sorted on the page.
+ *  - Each URI, if present, is not empty.
+ */
 class ValidNFTokenPage
 {
     bool badEntry_ = false;
@@ -342,6 +353,19 @@ class ValidNFTokenPage
         beast::Journal const&);
 };
 
+/**
+ * @brief Invariant: Validates counts of NFTokens after all transaction types.
+ *
+ * The following checks are made:
+ *  - The number of minted or burned tokens may only be changed by
+ *    NFTokenMint or NFTokenBurn transactions.
+ *  - A successful NFTokenMint must increase the number of NFTokens.
+ *  - A failed NFTokenMint must not change the number of minted NFTokens.
+ *  - An NFTokenMint transaction may not change the number of burned NFTokens,
+ *  - A successful NFTokenBurn must increase the number of burned NFTokens.
+ *  - A failed NFTokenBurn must not change the number of burned NFTokens.
+ *  - An NFTokenBurn transaction may not change the number of minted NFTokens.
+ */
 class NFTokenCountTracking
 {
     std::uint32_t beforeMintedTotal = 0;

From 8301c729a89e027e17ed58cfcb51e3a459d074cc Mon Sep 17 00:00:00 2001
From: Scott Schurr <scott@ripple.com>
Date: Mon, 5 Jun 2023 14:46:08 -0700
Subject: [PATCH 2/3] [FOLD] Change "may" to "can" and "may not" to "cannot"

---
 src/ripple/app/tx/impl/InvariantCheck.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/ripple/app/tx/impl/InvariantCheck.h b/src/ripple/app/tx/impl/InvariantCheck.h
index 50c422f938a..c835ece7075 100644
--- a/src/ripple/app/tx/impl/InvariantCheck.h
+++ b/src/ripple/app/tx/impl/InvariantCheck.h
@@ -357,14 +357,14 @@ class ValidNFTokenPage
  * @brief Invariant: Validates counts of NFTokens after all transaction types.
  *
  * The following checks are made:
- *  - The number of minted or burned tokens may only be changed by
+ *  - The number of minted or burned NFTokens can only be changed by
  *    NFTokenMint or NFTokenBurn transactions.
  *  - A successful NFTokenMint must increase the number of NFTokens.
  *  - A failed NFTokenMint must not change the number of minted NFTokens.
- *  - An NFTokenMint transaction may not change the number of burned NFTokens,
+ *  - An NFTokenMint transaction cannot change the number of burned NFTokens.
  *  - A successful NFTokenBurn must increase the number of burned NFTokens.
  *  - A failed NFTokenBurn must not change the number of burned NFTokens.
- *  - An NFTokenBurn transaction may not change the number of minted NFTokens.
+ *  - An NFTokenBurn transaction cannot change the number of minted NFTokens.
  */
 class NFTokenCountTracking
 {

From 4f40b8a86eab24f65ec4dacfac04bc5607fad960 Mon Sep 17 00:00:00 2001
From: Scott Schurr <scott@ripple.com>
Date: Wed, 7 Jun 2023 10:33:39 -0700
Subject: [PATCH 3/3] [FOLD] Respond to further review comments

---
 src/ripple/app/tx/impl/InvariantCheck.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/ripple/app/tx/impl/InvariantCheck.h b/src/ripple/app/tx/impl/InvariantCheck.h
index c835ece7075..fe17db44fa7 100644
--- a/src/ripple/app/tx/impl/InvariantCheck.h
+++ b/src/ripple/app/tx/impl/InvariantCheck.h
@@ -324,7 +324,7 @@ class ValidNewAccountRoot
  * The following checks are made:
  *  - The page is correctly associated with the owner.
  *  - The page is correctly ordered between the next and previous links.
- *  - The page contains a valid number of NFTokens.
+ *  - The page contains at least one and no more than 32 NFTokens.
  *  - The NFTokens on this page do not belong on a lower or higher page.
  *  - The NFTokens are correctly sorted on the page.
  *  - Each URI, if present, is not empty.