Legacy Interface Extensions is somewhat unclear

[gsnedders]

https://w3c.github.io/webrtc-pc/#legacy-interface-extensions opens with:

Supporting the methods in this section is optional. However, if these methods are supported it is mandatory to implement according to what is specified here.

It then defines various "method extensions": these are just defining behaviour for given operation overloads — I don't think it is intended that RTCPeerConnection interface's createOffer operation is optional to support (i.e., what I'd expect "the createOffer method" to refer to, thus what I'd expect "the methods in this section" to refer to), just that that specific overload is optional to support.

It's also to me somewhat unclear whether this text allows you to support the legacy createOffer overload but not the legacy setLocalDescription overload; i.e., can you support some of the legacy overloads, or is it meant to be all or nothing? They're optional, but is that collective or individual — the second sentence quoted above makes me think the intention is collective, but it could be clearer.

Then we reach the "Legacy configuration extensions" — and here it is very unclear what the implementation requirement is. Dictionary members are in no way methods, and the createOffer(optional RTCOfferOptions options = {}) override is mandatory to implement, so it doesn't obviously fall under the "supporting the methods in this section", which… implies supporting them is mandatory? But I don't think that's the intention.

We should clarify the conformance requirements for this section.