> The difference is that in Matrix there's only one specification which servers & clients can be compliant or not compliant with. Whereas in XMPP, there's an ar

> The difference is that in Matrix there's only one specification which servers & clients can be compliant or not compliant with. Whereas in XMPP, there's an arbitrary combinatoric explosion of XEPs which you may or may not be compliant with. We don't version XMPP in this way, but instead annually publish the "compliance suites" listing the required XEPs for a range of profiles: https://xmpp.org/about/compliance-suites/ https://xmpp.org/about/compliance-suites/ - so for example an XMPP client can be compliant with the 2021 mobile requirements. In this document we also hint to developers which XEPs are looking promising for the future, so they have ample notice to play with them and give feedback. Beyond the compliance suites, implementations are obviously free to experiment with other XEPs, and that experimentation feeds into the standards process and determining what will be in the following year's compliance suite.