Select, but returning binary data.

Hi all,

I can't figure out how to issue a select statement that will return
binary data instead of textual data.  (pgSQL backend message "B"
instead of "D".)

I'm also having some trouble finding documentation about "function
calls", and what their use is.  Is their anyone out there using that
animal, or is everyone happily using functions in regular queries?
If someone could direct me to some sample function call statements,
and their result...

Thanks,

Marc