[DFDL-WG] clarification: DFDL behavior of intersect, except operators

[Mike Beckerle]

Some time back there was an erratum to add intersect and except operators
from XPath 2.0 to DFDL. I believe these were in use by the DFDL4S flavor of
Daffodil, and so were added to DFDL v1.0.

Are these operators restricted to accept or to produce 0 or 1 node only,
or are they able to accept and produce lists of nodes that can then be
counted with fn:count, for example?

I guess I have lost track of the use-cases for these. The XPath 2.0
definition of these operators is of course fully general, accepting
multiple node sequences, and producing multiple-node sequences. That would
mean the ultimate result of these operators could be a sequence of more
than one node, and that means it would have to be an argument to fn:count,
fn:exists, .... not sure what other functions. They could never be the
direct result-producing part of an expression.

Can someone point me at the use case for these again?

Mike Beckerle | OGF DFDL Workgroup Co-Chair | Owl Cyber Defense |
www.owlcyberdefense.com
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