[DFDL-WG] empty sequences

[Mike Beckerle]

This section of the spec seems wrong:

14.1 Empty Sequences
A sequence having no children is syntactically legal in DFDL. In the data
stream, such a
sequence can have non-zero length LeftFraming and RightFraming regions, but
the
SequenceContent region in between must be empty. It is a processing error
if the
SequenceContent region of an empty sequence has non-zero length when
parsing.

XML schema does not define an empty sequence that is the content model of a
complex type
definition as effective content so any DFDL annotations on such a construct
would be ignored. It
is a schema definition error if the empty sequence is the content model of
a complex type, or if a
complex type has nothing in its content model at all.

This seems like it is both legal and useful:

<complexType name="headerRowType">
   <sequence dfdl:initiator="name%WSP+;address%WSP+;phone"
dfdl:terminator="%NL"/>
</complexType>

So the statement, DFDL annotations on such a construct would be ignored, is
not right.

And also a complexType sequence might actually have content via
dfdl:hiddenGroupRef.

<complexType name="hiddenGroupType">
   <sequence dfdl:hiddenGroupRef="myHiddenGroup"/>
</complexType>

So the statement that the region in-between left and right framing must be
empty is also not right.

Comments?


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