US or UK spelling in the standard?

[hoijui]

Especially important for the properties in the actual technical specification, e.g. organization vs organisation.

Is there some international standard/guideline for which to use?

For long-term historical reasons, one could assume it would be UK spelling, but given that this is an IT standard, and a huge part of modern IT standards originated in the US, one could just as much assume this as the more fitting option.

[hoijui]

GitHub for example, has organizations, not organisations.

Alternative: Try to avoid words with differences altogether?

StackOverflow supposedly prescribes US spelling for its own tags: https://meta.stackexchange.com/a/23873/384667

A more general and at the same time more fitting question about the topic on SO: https://stackoverflow.com/questions/157807/gb-english-or-us-english \ -> Use US spelling in code and tags and the like

[moedn]

seems like en-US seems by far the most commonly used variant :) en-GB was only used because it's the standard language in EU projects, but for OKH-LOSH I'd be in favor for en-US

[hoijui]

US it is!