NOTATION FPIs (was: <XML:SCRIPT>)

[Michael Kay]

>It *is* useful: it's an opaque string, which can be used to
look up
>components (programs, beans, shared libraries...), just as
MIME types
>can.  You never asked for a set of maintained MIME-type
servers like
>DNS.  In fact, it's not difficult to write an FPI for a
MIME type:
>
> -//Internet Assigned Numbers Authority//NOTATION MIME
image/gif//
>
Perhaps I'm being pedantic, but I think it's worth pointing
out that there's no such thing as an FPI in XML. The closest
there is is a "Public Identifier", and the only things that
the spec says about it are (a) that certain spaces within it
are insignificant, and (b) that the processor can try and
convert it to a URI (but it doesn't say how).

For the perceptive reader, the choice of name for the
metasymbol suggests that the authors were thinking of some
kind of global namespace, and the examples of Public
Identifiers suggest they were thinking of some kind of
analogy with a similar namespace used in SGML. But this is
reading between the lines of the standard.

It's actually even easier to write a Public Identifier for a
MIME type, if I can choose I can call it "image/gif", or
even "fred".

Mike Kay


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