I'd like to challenge the assumption that an explicit call for adoption
is required if work is mentioned in a charter. Sometimes, if work is
mentioned as a possible starting point, that's true. However for
working groups like the original XMPP, DKIM, ABFAB and BEEP, where work
was mentioned as a basis/as *the* starting point, the question of
whether to adopt the work happens as part of the chartering process.
I'm not sure that impacts how IPR is handled; in that case I'd expect
the IPR to be confirmed/discussed as part of the chartering process.