Processing instructions (was XSchema: Sections 5.0 and 5.1)

John Cowan cowan at
Fri Sep 25 17:10:54 BST 1998

Michael Kay scripsit:

> I'm designing a document type. Is there any circumstance
> when you would advise me to use a Processing Instruction
> rather than an empty element with attributes? I can't think
> of one myself, but I'm sure the XML designers must have had
> something in mind.

Probably not.

PIs are extremely useful when adding information to documents with
frozen DTDs.  For example, the proposed "xml:stylesheet" PI allows you
to attach a stylesheet to any XML document without having to
tamper with the document's DTD (as by adding a STYLE element
or attribute).

I can't see designing a new document type and using PIs, though.
As you say, elements or attributes do the work.

John Cowan		cowan at
	You tollerday donsk?  N.  You tolkatiff scowegian?  Nn.
	You spigotty anglease?  Nnn.  You phonio saxo?  Nnnn.
		Clear all so!  'Tis a Jute.... (Finnegans Wake 16.5)

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