Is the XML decl a PI ?

Tim Bray tbray at
Sun Nov 14 18:27:35 GMT 1999

At 01:49 AM 11/14/99 -0000, Richard Anderson wrote:
>> It is not a "processing instruction"!  It is a *declaration*!
>The XML declaration is an indication to the application processing the
>document as to what version of the XML spec the following markup conforms
>to, what encoding is used, and whether or not there are dependancies of
>external entites within the document.  

This is true.

But it's my opinion that the XML decl is *not* a PI, for three reasons:

 - it doesn't match production [17] because the target is 'xml'
 - it doesn't match sections [22] and [27], which says that a PI
   can only occur in the space starting *after* the XML declaration
 - section 2.6 says "Processing instructions (PIs) allow documents to 
   contain instructions for applications. ".  The XML decl contains 
   instructions for the XML processor which is carefully distinguished
   from an application

But I think the spec probably should have had an explicit statement
saying that the XML decl either is or isn't a PI, because it admittedly
kind of walks, swims, and quacks like one. -Tim

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