Re: Versioning and HTML

Jonathan Rees <jar@creativecommons.org> writes:
> So version indicators only support extensibility (or whatever other  
> goal you're after) if the future consequences for both old and new  
> consumers are articulated and documented before the whole process gets  
> started.

But that's not uniquely true of version indicators, is it? That's true
no matter what technique is used to distinguish one version from
another. The alternative, where there aren't any version identifiers,
requires consumers to deal with both old and new markup as well.

For some languages and some applications, it may be reasonable to
define a universal semantics for all versions, such as the HTML rule
of ignoring wrappers it doesn't recognize. (Not that that hasn't
introduced problems of its own, with special elements created over
time just to work around the consequences of the "ignore wrappers"
rule.)

For other languages and other applications, it may not be reasoanble
to define a universal semantics. Applications must be expected in that
case to do something else. Version identifiers offer a convenient
mechanism to help users distinguish between versions, even if machines
don't need them: "Unexpected element 'fribble' encountered in this
V1.2.3 document. The element 'fribble' is not defined in V1.2.3."

                                        Be seeing you,
                                          norm

-- 
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http://nwalsh.com/            | of men of old; seek what they
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