Multiple content codings are possible

[martinthomson]

However, this text from item 4 implies otherwise.

If multiple content-codings are acceptable, then the acceptable content-coding with the highest non-zero qvalue is preferred.

I think that this only applies if the server wishes to choose between codings, as opposed to apply them all. Compression codings are usually mutually exclusive, but other codings are not necessarily. Splitting this point into a paragraph might be the way to resolve this:

A message can include multiple content codings [I think no hyphen is correct], but some codings, such as those that compress content, can be redundant. When selecting between multiple redundant content codings, the acceptable content coding with the highest non-zero qvalue is preferred.

[reschke]

See also #719