P.I's

[John Cowan]

Peter Jones wrote:

> <!NOTATION  avi  SYSTEM "C:\mydir\aviplay.exe" >
> <?avi  holidays.avi?>

That would be better managed with an unparsed entity and this DTD:

<!-- declares avi notation: note that system ids are URIs -->
<!NOTATION avi SYSTEM "file:///C:/mydir/aviplay.exe">

<!-- declares unparsed entity -->
<!ENTITY Holidays SYSTEM "holidays.avi" NDATA avi>

<!-- declare useful element -->
<!ELEMENT Play-it EMPTY>
<!ATTLIST Play-it
	what	ENTITY	#REQUIRED>

and then in the document instance:

<Play-it what="Holidays"/>

> Is this the sort of thing?

A better use for PIs is to instruct programs that filter or otherwise
interpret XML.  For example, there is a (non-standard) PI for
attaching a stylesheet to a document for rendering purposes:
architectural forms processing (which is essentially a scheme
for mapping idiosyncratic elements or attributes into ones defined
by a standard called an "architecture) use a PI to name the
architecture and give useful details about it, etc. etc.

-- 
John Cowan	http://www.ccil.org/~cowan		cowan at ccil.org
	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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