Document or sequence

|    Mohamed: I'm concerned about the consistency of viewport-source,
|    iteration-source, and xpath-source.
|    ... I don't find the explanation about why some are one way and some are
|    not very clear.
|    ... I think sequences are just not very clear at a deep level.

I think the rationale is this:

1. We decided that components do not do iteration implicitly. You
   can't send a sequence of documents to a component that only accepts
   a single document expecting it to process each document in turn.

2. A for-each component is designed to iterate over sequence, so it
   has to accept a sequence.

3. A viewport component takes a single document so it can't take a
   sequence (see point 1).

4. I don't believe that XPath 1.0 defines the semantics of applying an
   XPath expression to a sequence of documents, so xpath-context can't
   take a sequence.

Does that help at all?

                                        Be seeing you,
                                          norm

-- 
Norman Walsh
XML Standards Architect
Sun Microsystems, Inc.