startIndex
Discussed during the WFS 3.0 Hackathon:
In #23 we removed startIndex, because it can be hard to implement in some environments. It, however, is useful and it should be added in an extension.
consider this use case:
Client software, supporting OWS and OGCAPI standards, which has an embedded pagination mechanism based on counters (no links) would need to parse the self-link to extract the startindex to be used in the generic pagination mechanism. This is quite error prone.
Personally I would make startindex a required response parameter in OGC API Common
It was a deliberate decision to also support servers and clients that do not page via counters and I think that still makes sense. So, the idea is to add an offset/startindex query parameter in a future requirements class. This extension is part of the list (#451), but this wasn't mentioned as a priority by anyone when it was recently discussed, so it is not part of the current charter update request.
Also, offset/startindex should not be mandatory in Common Part 2, at least if it is the idea that a future Features Core would normatively reference Common.