Inconsistent colour / color

[chrisn]

A minor issue, sorry. Should we pick one and use it throughout the spec?

[svgeesus]

The original PNG spec from 1996 used color. see for example 2.2 Color values.

The reason being that the W3C style guide says, for spelling

W3C uses U.S. English (e.g., "standardise" should read "standardize" and "behaviour" should read "behavior").

PNG Second Edition in 2003 used colour, see for example 4.2 Colour spaces.

The reason being that it was also published with identical content as ISO/IEC 15948:2003 (E) and ISO style rules require the use of International English (i.e. English without Webster's US-specific spelling reform of 1828)

( I remember when Lilley et. al Colour in Computer Graphics was published in the UK in 1993 and made available online, I rapidly got a comment that "You have mis-spelled color, not just once, but throughout! Did you not think to use a spell checker?")

Of course whichever is chosen there will still be inconsistencies - If we use International English throughout, we will still refer to the International Color Consortium for example.

But I agree we should be consistent where possible and my preference would be to follow the W3C style guide and all other W3C specs and use the US English spelling.

Note that the links embed the spelling choices too:

https://www.w3.org/TR/REC-png-961001#DR.Color-values
https://www.w3.org/TR/2003/REC-PNG-20031110/#4Concepts.ColourSpaces

Given that the First Edition was in force for 1996-2003 and the Second Edition from 2003-2023 we should preserve link compatibility on fragment identifiers with the Second Edition, which we have been doing.

https://www.w3.org/TR/png-3/#4Concepts.ColourSpaces

[ProgramMax]

I feel like early in Third Edition development I read something (likely W3C?) saying to use international English. Maybe I'm misremembering.

In either case, I agree we should be consistent without breaking inbound links.

[svgeesus]

PR to use color in visible text, while preserving colour on inbound links.

• Use US-English color in visible text, preserving incoming links that … #411

[Crissov]

Behaviour and neighbour(ing) also still consistently spelled with an u.

There are also some -ise spellings:

• perceptual quantiser
• optimise
• standardised

The text consistently uses grey and greyscale instead of US gray.

[chrisn]

I added a commit to #411 to fix those, apart from grey/greyscale as I'm unsure on how to preserve incoming links.