scripts and PIs

Eve L. Maler elm at
Fri Oct 15 12:49:47 BST 1999

At 03:17 PM 10/15/99 +0800, Rick Jelliffe wrote:
>                    Element   PI     Attribute
>-----------------  --------  ------ ---------
>Push/pull          Push      Push   Pull
>effect/structure   structure effect structure

This is a very useful matrix; it explains neatly something I've been trying 
to articulate about XML processing.  It's pretty harmless to add attributes 
to a document, because "by default" they don't get used in the output 
stream, but for formatting, elements must all be "consumed" somewhere by 
default.  For data-oriented processing, everything seems to be pull, though.

By the way, the main reason why we changed the closing delimiter of SGML 
PIs from > to ?> in creating XML was to make PIs safer for containing 
scripting and code.  It's pretty common to have the string ">" appear in 
scripting, but (we hoped) far less common to have "?>".  Besides, it made 
it more symmetrical...


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