(2) inconsistent specification
Contrary to the text in Section 4.6 (see above), Section 5 of RFC 4566
specifies, at the bottom of page 7:
An SDP session description is entirely textual using the ISO 10646
character set in UTF-8 encoding. SDP field names and attribute
names
use only the US-ASCII subset of UTF-8, but textual fields and
attribute values MAY use the full ISO 10646 character set. [...]
These conflicting specifications might become a source of
interoperability problems, and therefore, the conflict should be
resolved by a clarification !!!
Note: Subsequent text in sections 5.* specifies behaviour related
to the "a=charset" attribute required if other charsets than UTF-8
are used in certain fields; therefore, the latter exclusive UTF-8
rule is most probably too restrictive and hence inappropriate.