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WD-webarch-20031209: Extensibility is a not a property of languages in isolation

From: C. M. Sperberg-McQueen <cmsmcq@acm.org>
Date: 05 Mar 2004 00:13:04 +0100
To: W3C TAG mailing list <public-webarch-comments@w3.org>
Message-Id: <1078441983.2531.13.camel@localhost>

1.2.2 para 5 ("Ideally, many ...").  Sentence 2 ("Languages that
exhibit this property are said to be 'extensible'") seems to say that
if an instance of a larger language can be processed as though it were
an instance of a smaller language, then the larger language is said to
be "extensible".  I think the term is probably better taken as
referring to the smaller language; I think the paragraph should
probably be rewritten from scratch, since with the current structure
it will be difficult to provide a clear antecedent of the phrase "this
property".  

In any case, the current formulation invites the reply that OF COURSE
some instances of a superset language may be processed as if they were
members of a subset language: in any plausible case, a large number of
members of the superset language ARE members of the subset language;
that is what it means for one language to be a superset of another.  I
think the instances you wish to refer to particularly are those
members of the superset language which are NOT instances of the subset
language, but which can nonetheless successfully be processed by a
suitable processor.  The analysis here is weakened by its failure to
acknowledge explicitly that the property in question is not a property
of the language by itself but a property of the particular kind of
processing involved, and the coding of the processor.  (Here as
elsewhere the document appears to fall into the trap of speaking as if
only one kind of processing were liable to be applied to any
particular document, or any particular language; this is not the case
for any language intended to promote the reuse and repurposing of
data, and that fact is of material importance in any discussion of
extensibility.)
Received on Thursday, 4 March 2004 18:13:55 GMT

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