Accessing declared value of attribute in Jade

[Daniel Speck <dspeck@xxxxxxxxxxxx>]

I am trying to write an application using Jade's SGML backend that
breaks-up an SGML document into components at various levels in the
hierarchy of the document. I would like to be able to obtain a list of
all external entities refered to at each level so that I can construct
an appropriate document type declaration subset for each fragment. 

For example, say a book contains chapters and I want to break up the
book by chapter. For each chapter I would like to obtain a list of all
external entities refered to in that chapter.

I have run into a problem that I can't seem to solve. For each element
in the instance I need to find the declared value of each non-implied 
attribute and if it is ENTITY or ENTITIES, I need to do further
processing to obtain the external identifier(s) and notation(s). The
problem I am having is that I can find no way to obtain information
about the declared value of an attribute. Can anyone tell me how?

-dan

-- 
Daniel Speck                              e-mail: dspeck@xxxxxxxxxxxx
Research Engineer                          voice:     +1 301.548.7818
Thomson Technology Services Group            fax:     +1 301.527.4094
1375 Piccard Drive, Rockville, MD 20850      WWW:    www.thomtech.com

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