[DFDL-WG] Clarification: attributes in DFDL schema that are used not for data, but for other non-DFDL annotation elements.

[Mike Beckerle]

Interesting issue.

DFDL doesn't allow use of attributes.

But we have a user that has a DFDL schema to which they also want to add
other non-DFDL annotations.

Like DFDL itself, this other annotation language has a variety of
annotation elements that appear inside xs:appinfo blocks with specific
source attribute specified. A DFDL processor should be ignoring these.

Those other annotation elements have attributes (as do DFDL's annotation
elements.)

But Daffodil issues a schema definition error on the attribute declarations
of this other annotation-language schema. This because it has no way of
telling if these attribute declarations are for use *only* in annotations
that it will ignore, or if they are used for modeling data.

Question is: Is it acceptable for a DFDL annotation to just say "Nowhere in
the extended schema - all files - can there be any attribute
declarations.", or do we need to accommodate attributes and in fact every
XSD construct that DFDL disallows, so long as they're not being used to
model data?

Really there's two questions here. First, does the DFDL specification take
(or need to take) a position on this. Second, what's a practical choice for
a DFDL implementation like Daffodil to take here.

...mikeb

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