In this case, "text + formatting" or "html + formatting" is just
another kind of "PDL".
# o the client needs to display or not display some attributes based on
# the type of the document. Either the server needs to receive the
# document type, or it needs to send information to the client about
# attributes that are restricted to certain document types. I favor the
# later approach.
I don't think those are the only two cases. There's also:
- the client knows which attributes are appropriate for a given
document type (how printing works now)
- the server informs the clients of additional required parameters
after the document has been submitted.
I favor doing the first and the second when necessary.
# o the protocol needs to be able to specify whether an accompanying
# attribute has been embedded in the document and is just there to
# indicate the needed resources if it is present.
I think generally that job attributes could to be marked as either
overriding or subordinate to attributes embedded in the document,
although "always override" would work.
# o it may be useful for a printer to indicate that it only understands
# an attribute if it is embedded in the document so that a client knows
# whether to embed it. This concept is probably most useful in a ppdfile
# context which describes either the PDL string to embed or the attribute
# to set.
This may be useful but not very. By the time you add the code to the
printer to tell the client that "this printer doesn't understand that
attribute if it isn't embedded", you might as well have fixed it to
actually understand it.