Inheritance in XML [^**]

james anderson James.Anderson at mecom.mixx.de
Thu Apr 23 18:01:29 BST 1998


hello again,

Tim Bray wrote:
> 
> At 03:51 PM 4/23/98 +0200, james anderson wrote:
> >the recommendation does, in deed, assert a semantic for xml documents.
> ...
> >the xml recommendation defines a two relations among elements (subsumption and
> >precedence), defines a (yes) language for describing these relations (the dtd
> >entities), asserts three states for documents (valid, invalid, and
> >unspecified), and specifies how to infer which state a document is in based
> >its content.
> >
> >this is a "semantic"....
> 
> Reasonable people may disagree.  I believe that sequence and
> containment are purely syntactic in nature and imply no semantic
> whatsoever.

reasonable people also agree. i share your belief in this point.

> Similarly I see no "semantic" in asserting that my butt
> is currently placed on top of a chair, or that this chair is currently
> placed in front of my computer.

we also agree on that.

it is, however, a "semantic" when criteria are provided whereby the content of
the dtd permits one to assert that certain sequence and containment relations
are valid and others are not.
the semantic arises when you have a description which says that your butt on
the chair and the chair in front of the computer conforms to osha workplace
guidelines together with guidelines for applying the descriptions. that's your dtd.

> 
> >it is disheartening to read where attention is deflected from the issue by
> >claiming that no semantic was intended.
> 
> Get real.

i am.

the problems with the dragging discussions on "inheritance" will persist at
least to the point where one recognizes: what semantic is entailed by the
recommendation as it stands; what possible semantics are not; that
"inheritance" has a meaning only in the context of a semantic for operations
and for a store; and what must be added to the semantic in order that one can
talk about using xml to serialize descriptions which denote inheritance relations.

that's all i'm saying :)

>  You may choose to argue that containment and sequence
> constitute, in some philosophical framework, "semantics",
i did not and do not.
i observe that, when taken together with other aspects of the xml
recommendation, they do, in fact, constitute a semantic.
> but the claim
> that no semantic was *intended* is unchallengeable because in point of
> fact when we wrote the spec we considered that what we were describing
> was syntax. -Tim

i am not concerned with the *intention*, as such. i have no direct knowledge
of what the authors intended. to be honest, the intention itself doesn't
matter. my discussion is (and was) aimed at the results, and perhaps
indirectly at the effect of discussing intention. i am concerned that is not
productive to abide by what may have well been the intention, or to use it as
a point of argument now that the recommendation stands.
a semantic is now "part of the problem". it does not matter, that it was not before.

bye for now,


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