Based on Mo Zanaty's review comments.

Response to comments from Mo Zanaty. Using "muxer/demuxer"
really isn't less ambiguous than "encoder/decoder" but does
help distinguish between this draft and a 'codec encoder/decoder'
described by the Opus RFC.

This version resolves some issues with the packet size limits
 raised by Mark Harris.

1. Removed an inappropriate normative MAY.
2. Gave an explicit range of sample rates deemed to be "non-crazy".
3. Give explicit guidance on packet sizes that SHOULD and MAY be rejected.

This is just a should, so we want to leave the RFC 6716 reference
to the second occurance, but using the same language ties them
together and to the later occurances.

The Opus RFC doesn't really say what to do beyond rejecting
a particular packet, but having the reference reinforces that
we're trying to leverage the same constraints in the specific
context of ogg encapsulation, and this isn't a new rule.

Suggestion from mark4o.

This avoids confusion with the number of frames being defined
by more than the first byte with code 3 packets.

Patch from mark4o.

The macros take arguments, they aren't just constants. Thanks to
mark4o for the report.

Add a limit of no more than 6 characters for these tags' values.

SHOULD or SHOULD NOT. There is no attempt.

From the codec wg mailing list thread
https://www.ietf.org/mail-archive/web/codec/current/msg03107.html

These are normative whether capitalized or not. Capitalize the ones
which make sense as normative requirements, and reword the rest.

We want to general guidelines for stream-level encapsulation to
apply to multiplexed as well as degenerate streams. 'Files' can
therefore specific to the mine-type discussion for unmultiplexed
Ogg physical streams.

These are the changes proposed in
 <http://www.ietf.org/mail-archive/web/codec/current/msg03058.html>,
 with some minor additions (see follow-up on the list).

Promote the new tag definitions to a separate subsection,
balance tags, improve wording, and document our motivation
for the R128 tags.

Thanks to Calvin Walton for pointing this out.

Patch from Greg Maxwell in response to implementor feedback.
https://www.ietf.org/mail-archive/web/codec/current/msg03053.html

Bump version and date for draft-ietf-codec-oggopus-03 submission.

Move more text into figure pre/postamble to fix rendering issues
in the xml2rfc html output. These need to be manually re-indented
in the txt output before submission. :(

Fix resampling frequency choice algorithm, which was missing a word.

Fix some spelling and make some minor enphasis changes.

These aren't available over https, but actually work, unlike
the old reference urls.

Fixes a nit.

Fixes a nit. According to idnits, 'NOT RECOMMENDED' is optional,
but we use it. Other words, like SHALL which we don't use are
required in the boilerplate.

This seems to be the correct way to represent institutional authors
in the references.

and use them more strictly in the rest of the text.