LPDs [Was: [xml-dev] Summary of critiques of XML Namespace from comments to James Clark 2010 blog]

On 24/07/2021 09:26, Marcus Reichardt wrote:
...
> (Now SGML also has LPDs, a type of declaration set available in 
> addition to DTDs, to basically do the same thing, and that can be
> even pipelined OOTB; it's unclear to me why archforms didn't extend
> LPDs but rather invented it's own IS10744 PI for basically the same
> thing without adding power where it was needed, such as for dealing
> better with attribute mappings or filtering).

I don't have such a rosy recollection of the Link Process Definition
(LPD) facility.  Back in the day, we used it exactly once, and the LPDs
were dropped as soon as we could replace them with proper software.

LPDs could add attributes to elements based on the element's context,
yes.  This works well enough in the two-level toy example in the SGML
Handbook, but if you need more context, you end up with an explosion of
LPDs for the different contexts.

The utility of putting style information as part of the validation never
made sense to me either.

I wouldn't count LPDs as one of the useful features of SGML.

Regards,


Tony Graham.
-- 
Senior Architect
XML Division
Antenna House, Inc.
----
Skerries, Ireland