The usage of the 'bundle-only' attribute is only defined for a
bundled "m=" line with a zero port value, within an offer. Other
usage is unspecified.
The answerer MUST NOT associate an SDP 'bundle-only' attribute with
any "m=" line in an answer.
May want to clarify that although implementations of this specification will not generate 'bundle-only' in an answer, they should be prepared to receive it and not treat it as an error.
These two statements seem contradictory to me:
May want to clarify that although implementations of this specification will not generate 'bundle-only' in an answer, they should be prepared to receive it and not treat it as an error.