RE: [dita] Action: Eliot on lockmeta updates

There is perhaps a fifth case to add to Eliot's four.

>>>>
1. The topicref's metadata is used exclusively as the effective metadata for
the topic and the topicref.

2. The topic's metadata is used exlclusively as the effective metadata for
the topic and the topicref.

3. The topicref's and topic's metadata are merged, with metadata items from
the topicref overriding the same metadata items from the topic (where "same"
may not be clearly definable in all cases, but that's a separate issue).

4. The topicref's and topic's metadata are mered, with metadata items from
the topic overriding the same metadata items from the topicref.
<<<<

5. The topicref's and topic's metadata are merged, with metadata items from
both the topicref and the topic being used (where multiple metadata items
are valid).


For example, with ua-context elements of:

Topicref -> <ua-context id="123" />
Topic    -> <ua-context id="654" />

the result of the five cases would be:

1. <ua-context id = "123" />
2. <ua-context id = "654" />
3. <ua-context id = "123" />
4. <ua-context id = "654" />
5. <ua-context id = "123" /><ua-context id = "654" />


Cheers

Tony Self