From: Su-Laine Yeo
Sent: Tuesday, April 14, 2009 2:45 PM
Subject: RE: [dita] Inheritance of attributes through mapref
merging vs. overriding for conditional attributes, let’s consider the following
example: You are creating a document for three audiences, A, B, and C. The map
a topic that is common to all audiences
a topic in which the entire topic is for audience A only
a topic which does not apply to A at all, and contains some elements that apply
only to B and some elements that apply only to C
generating output for audience A, you will want to include topic 1 and 2. Topic
3 should not appear at all, not even in the TOC.
generating output for audience B, you will want the TOC to include topic 1 and
topic 3. Topic 3 should include any unconditional elements, include the
elements that apply to B, and exclude the elements that apply only to C.
the OT gives the desired behaviour if you set audience=”a” on the topicref to
topic 2 and audience=”b c” on the topicref to topic 3. If we were to say that
audience attribute values on a topicref are added to the conditional attributes
within the target topic, you would not get the desired behaviour in this case,
because when generating output for audience B, you would get all the content
for audience C in topic 3. I have thought of trying to get the desired
behaviour by explicitly conditionalizing all of the elements in topic 3 instead
of putting conditions on the topicref, however this is not feasible because you
cannot conditionalize element types such as <title>.
I think this particular example supports a rule that conditional attribute
values should be processed as the intersection as of the values on the topicref
and the values on the further down the hierarchy. I think this is the rule
which is actually implemented in the current OT.
Interaction Design Specialist
JustSystems Canada, Inc.
> The two open questions are:
> 1) What about attributes like @audience, which take
multiple values? If my
> map reference has audience="a b", and the
map has audience="c", does "a b"
> override "c", or does this result in
"a b c"? If the latter, we will need
> to come up with an authoritative list of which
attributes act this way (as
> opposed to the override behavior of @toc and
Don’t we already have a list for
the later case (merge)? If an attribute value cascades and the attribute
allows multiple values then. it merges. If an attribute value cascades
and the attribute does not allow multiple values. it overrides.
My goal here is just to make the
rules for map to map cascading as much like the rules for other cascading as
possible because that is more consistent and therefore easier to remember.
And while the DITA 1.1 spec. didn’t talk about map to map cascading
explicitly, when it did talk about cascading more generally it talked about
merging multi-valued attributes and overriding single values attributes. So it
just seem unnec3essairly complicated to introduce a new case. Note too
that this question is about general cascading and that there are separate rules
for conref behavior.