topicref to map - draft of recommended behavior

[Michael Priestley <mpriestl@ca.ibm.com>]

Here's what I think we agreed on in
today's call - making it three paras, one to provide descrip of existing
default behavior, one to provide guidance for specialized processing, and
finally one to provide explicit guidance to specializers. I expect this
will require more tinkering, and hope I haven't missed any points - if
I have I welcome corrections:

--------------------------------
A generic topicref to a generic map
may be used to create an aggregated result, incorporating the contents
of the referenced map into the referencing map. When the topicref is to
a whole map, rather than an individual branch, then an aggregating process
may achieve a DITA -valid aggregated result by pulling the target map's
top-level topicrefs into the location of the referencing topicrefs, with
any reltables moved to the end of the referencing map to avoid having reltable
elements at invalid locations.
(see dita 1.1: http://docs.oasis-open.org/dita/v1.1/OS/langspec/common/theformatattribute.html

When a topicref points to a map and
either or both elements are specialized or contain specializations, the
type of the referencing element typically determines the DITA type of the
elements being pulled in. For example, a <chapter> reference to a
map implies that the target's top-level topicrefs will become <chapter>
elements. However, it may be desirable to preserve the semantics of the
referenced map's elements in any DITA-valid aggregated result. For example,
a <topicref> to a bookmap could be resolved into a set of topicrefs
with outputclass="chapter".  Typically an aggregating process
would not include literal elements from unknown specializations, since
it faces the risk of including specialized elements that are not valid
in the referencing context. 

When you create processing for a new
specialization of topicref, be aware of the following considerations:
- should it be able to reference other
maps?
- should it be able to referency any
type of map?
- is it valid for the target's top-level
topicrefs to be pulled into the reference's location, becoming multiple
instances of the referencing element type? (as described in the previous
paragraph)
- is it appropriate for the children
of the target element to be pulled in as generic topicrefs, with any additional
semantics preserved in some other manner (for example, outputclass)? (as
described in the previous paragraph)
If the answer to all of these is yes,
then the base-level aggregation policies should be appropriate. Otherwise
you will need to create overriding processing to ensure the aggregated
result is appropriate for your needs.





Michael Priestley, Senior Technical
Staff Member (STSM)
Lead IBM DITA Architect 
mpriestl@ca.ibm.com
http://dita.xml.org/blog/25