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List:       fop-dev
Subject:    FO Tree needing knowledge of Area Tree
From:       Glen Mazza <grm7793 () yahoo ! com>
Date:       2004-01-25 13:00:27
Message-ID: 20040125130027.77542.qmail () web60109 ! mail ! yahoo ! com
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Some of the previous heated discussion on whether the
FO tree could be created without knowledge of the Area
Tree apparently has been answered by the XSL
specification, with Peter West's view being correct. 
Property resolution *does* in some areas rely on
knowledge of the Area Tree, and the XML Result Tree
--> FO Tree --> Area Tree does not always occur in a
sequential manner.

If this issue comes up again, Peter, next time just
point to the spec!

Glen

http://www.w3.org/TR/2001/REC-xsl-20011015/slice3.html#fo-jc-intro

Ch. 3 Spec:

"Central to this model of formatting is refinement.
This is a computational process which finalizes the
specification of properties based on the attribute
values in the XML result tree. Though the XML result
tree and the formatting object tree have very similar
structure, it is helpful to think of them as separate
conceptual entities. Refinement involves

-propagating the various inherited values of
properties (both implicitly and those with an
attribute value of "inherit"), 

-evaluating expressions in property value
specifications into actual values, which are then used
to determine the value of the properties,

-converting relative numerics to absolute numerics,

-constructing some composite properties from more than
one attribute

Some of these operations (particularly evaluating
expressions) depend on knowledge of the area tree.
Thus refinement is not necessarily a straightforward,
sequential procedure, but may involve look-ahead,
back-tracking, or control-splicing with other
processes in the formatter. Refinement is described
more fully in [5 Property Refinement / Resolution]."

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