[DFDL-WG] Clarification: empty sequence - how can it be non-zero content length

[Mike Beckerle]

Section 14.1 states:

      It is a processing error if the SequenceContent region of an empty
sequence has non-zero length when parsing.

How is it possible for an empty sequence to have a non-zero length of its
content region?

I understand it could have delimiters outside the content region, and other
framing possibly, but the content region has nothing in it then only
annotations can appear.
Annotations can be property definitions or can be DFDL statements. None of
those can consume representation bits when parsing, or produce
representation when unparsing.

So I believe this processing error cannot happen.

If I am correct, the statement about processing error should be dropped.

Also, clearly this statement does not apply to a sequence that carries a
dfdl:hiddenGroupRef, since the hidden group can contribute to the content
region. I would not consider a sequence carrying hiddenGroupRef to be empty
unless the referenced group is also empty.

Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology |
www.tresys.com
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