[dsdl-discuss] Re: Potential use cases for complex value validation from ebXML

Rick wrote:

>I think what we need to do for every non-SC 34 controlled vocabulary that
we use is to:

>1) Provide in an annex a normative "reference implementation" or "XML
binding" of that controlled vocabulary, comprising all the codes that have
ever been
used. Then maintain a non-normative public version in which codes are
added but never removed. Call them a namespace or something to distinguish
it from the standard. Implementations of DSDL use this list as their
default:
it means that any correct document that uses a code will pass, but it does
not
check that all codes are from the same period. Specify that
implementations
may augment this list (e.g. merge the one from the web) if new codes come
out and the reference list has not been maintained.

We should not be including any enumerated lists within the DSDL standard
suite (it goes against clearly stated SC34 policies). At best we should
point to some commonly used one in some registry maintained by someone else
(e.g. OASIS)

>2) Provide a mechanism by which implementations are allowed
as an option to use a particular version of a controlled vocabulary,
but this is by their own provision, not by ours.

This is a partial solution. What I think we should do is require that a
version-date attribute be assigned to any reference to an external list that
is to be used for validation purposes.

>3) Try to get the maintenance bodies to provide this list themselves.

Wishful thinking. ISO has been trying to get them to standardize on ASN.1
definitions for years, without success. Why should DSDL be any more
successful?

>Controlled vocabularies that are updated or obsoleted pose
difficulties for documents: a document that was valid at a
certain point in time should not become invalid just by the
passage of time *unless* the validation specifically includes
the semantic that the controlled vocabularies are the
most recent ones only.

This is the nub of the problem. Unless we ensure that validation rules are
clearly dated we cannot be sure that we can revalidate a document at any
time after its initial validation, because someone could have updated the
external code list between validations. Only if lists are maintained in
properly managed repositories, with roll-back capabilities, will we be able
to ensure revalidation of any document that references a list of options.
This would seem to point to the need to set up a properly managed OASIS code
list repository that can be referred to from DSDL schemas.

Martin

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