Steps to reproduce: look at https://en.wiktionary.org/w/index.php?title=kvaza%C5%AD&oldid=28810413

Expected outcome: no stupid complaints, no useless tracking cats

Currently "preview" can be detected by means of hacky

((f:preprocess ('{{REVISIONID}}') == '')

but there is no way to detect "older revision" ie viewing a revision other than the current one by explicitly picking it from the page history.

Who would benefit: end users and module developers.

Being able to distinguish "latest revision" vs "older revision" would allow modules to avoid complaints and tracking cats in the latter case, when such are blatantly pointless. Complaints and tracking cats should get fired only for "preview" and for "latest revision".

Proposed solution: add a function, comparable to

mw.isSubsting()

returning a tristate value depending on "latest revision" vs "older revision" vs "preview".