Your issue seemed to have been addressed here: https://forum.mendix.com/link/questions/5432
All functions are integrated in regular “Mendix functions” it seems.
Hope this helps!
Alternative solution: Documentation for old releases can usually still be found on github (or at least everything since the documentation pages were first made available on github).
The ‘context mechanism’ was described here: https://github.com/mendix/docs/blob/v1.0.0/refguide4/context-mechanism.md
I have never used it so I can't comment on your case, but hopefully the original documentation will get you what you need...
Indeed – it's a pity that the release notes of unsupported version are no longer available. You could perhaps have found it there in the release where the feature was introduced. My advice: submit a Request for Information on support.mendix.com and get the definitions that way.