[DFDL-WG] Are non-native attributes allowed on DFDL annotation elements?

[Mike Beckerle]

In XML Schema you are allowed to throw in attributes even just as
documentation i.e.,

<xs:element xmlns:rtfm="read:the:..manual." name="myElement" rtfm:yo="this
element name is general lameness" .../>

I.e, in the definition of xs:element there is this wildcard with standard
lax validation for any non-native attributes.

So, the question is do we want to also allow that on dfdl annotation
elements, i.e,

<dfdl:format byteOrder="bigEndian" rtfm:yo="it's LE Loser!" />

Given that you cannot nest <!-- style comments --> inside element syntax,
these non-native attributes are the only convenient way to add commentary
to the attributes of a XML document.

Another perhaps more compelling reason to tolerate this is that I am sure
in the next year all the DFDL implementation efforts are going to add some
new experimental properties, and we will want to hang them on the same dfdl
annotation elements. Schema inter-operation requires us each to tolerate
the other's such experimental properties to the extent that they are not
essential to the schema being usable at all.

So if I have:

<dfdl:element dafext:recursive="typesOnly"
xmlns:dafext="some.daffodil.urn.for.extensions"  ref="someOtherFormat" />

then we will want IBM DFDL and DFDL implementations generally, to perhaps
warn that it was there and unrecognized, but not to just SDE on
non-validation.

Today, the XML Schemas for DFDL Annotations do not allow non-native
attributes inside DFDL annotation elements, but the spec is silent on the
subject.

I was considering adding a couple of experimental properties (not right
away, but maybe by year end), and I only realized today that they would
break compatibility without a change here.

Comments?

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