Re: p:input doppelgangers

/ ht@inf.ed.ac.uk (Henry S. Thompson) was heard to say:
| So on further reflection, here's how I think it ought to be, and why:
|
|  p:viewport-source
|    (p:pipe | p:document | p:inline )?
|
|    That is, no change, because p:viewport is like a step with a single
|    required input.
|
|  p:iteration-source
|    (p:empty | (p:pipe | p:document | p:inline )+ )?
|
|    That is, exactly as p:input, because p:for-each is like a step with
|    sequence in and out, and should be allowed to be forced to iterate
|    no times and produce an empty sequence.

What's the point of writing a loop that explicitly iterates 0 times?
Putting p:empty seems entirely pointless to me and more likely an
error than not.

|  p:xpath-context
|    (p:empty | p:pipe | p:document | p:inline )?
|
|    A special case -- exactly one document, or none.  A dynamic error
|    if p:empty is used and a 'test' XPath expression appeals to the
|    context-node or context-position.

Yes, that was probably a brain cramp on my part.

                                        Be seeing you,
                                          norm

-- 
Norman Walsh <ndw@nwalsh.com> | If you're strong enough, there *are* no
http://nwalsh.com/            | precedents.--Scott Fitzgerald