COPY command, support for mixing binary and text columns?

Am I correct in the assumption that even though the network protocol
specifically allows individual columns of a copy command to be
binary or text format, the current COPY command in 8.3 doesn't
support specifying that?

Am I missing something in the network protocol which allows me
to specify it regardless of what the COPY command says?
-- 
Sincerely,          Stephen R. van den Berg.

In this signature, the concluding three words `were left out'.