How can I get XML cross-references to translate to Structured FrameMaker?

Question

I've been using Structured FrameMaker from the beginning, and have designed many EDDs, and about 10 years ago I did some translation of SGML into Structured FrameMaker (7.2) which worked well.
Now, (with FrameMaker 10), I've had to design an EDD to translate XML documents into Structured FrameMaker.
In my EDD I've a CrossReference element called XRef; this has an attribute of ID, which in turn has a value of IDReference and has Special AttributeConrols of ReadOnly.
My target elements in the EDD all have an ID attribute with a value of UniqueID.
My XML document's target xref element has  an attribute of linkend, and in XML this works as I'd expect.
When I pass the XML file through the EDD/Template, everything works except that I get an ID = no value, which, of course, results in no display of the cross-reference data in the document.
Oddly, in structured FrameMaker, my element of link, with an attribute of linkend, works as it should, and displays the data.  It may not be important, but the value for linkend is IDReference not UniqueID, and this displays correctly (I changed this attribute's value to Unique ID in my EDD and it made no difference to the XRef value in my document).
After making all these EDD changes, I've been careful to save the changes, import them to all files in my book and finally update the book.   Everything hangs together - except, of course, that the cross-reference doesn't work.
I'd sincerely appreciate any help or advice other users might have because I'm quite frankly stumped.

Answer 1

Russ,
Sorry about the delay in replying; got sidetracked trying to fix some FrameMaker 10 problems; on occasion, it laughs and crashes if we copy an element in a document and paste it to somewhere illegal.  This doesn't happen all the time, but it might be something someone might do, so it was interesting to know.
Anyway, back to cross-references.
In our r/w rules we have:
"linkend" is fm attribute "ID";
Can we also have a similar line under the cross-reference element as:
element "xref"
     is fm cross-reference element "XRef";
     attribute "linkend" is fm property cross-reference id;
     attribute "role" is fm property cross-reference format;
At the moment the second line is:
.....attribute ID is fm property cross-reference id;
I tried adding the attribute "linkend" is fm property cross-reference id; (so that I had both linkend and ID) bit but this made no difference.
In general use cross-references work, in that it picks up data in one place in the document, e.g. WorldWideWeb, and repeats it elsewhere.   So in our xml file we have a link element with an attribute linkend which, when it's processed (ignoring the handshake code used to link the two - which could be something vague like 12345vvdog), repeats whatever is the target.
Conversely, for a cross-reference, in xml they use an xref element which also has a linkend attribute (similar mysterious secret handshake behind the scenes) which is deemed to point to a list of references.   This looks like it might be the stumbling block in that it links to an area in the xml document which is used as an internally generated list of references.  Apparently this is only built when the xml book equivelent is finalised, so is not, like the link and linkend coupling described above.
I've passed this back to the xml people, and they are investigating a different way of preparing their cross-reference to a list of references (I'm now thoroughly confused with all these references - good thing the weekend's just around the corner).
I appreciate all you help and advice, I'll admit that this is a lot more difficult to understand than straight-forward EDD element creation along with their respective attributes.   Life used to be so much more simple back then!
In sum, what I thought I was doing was allowing an ID attribute with a value of IDReference in my elements, this was deemed to allow for FrameMaker cross-referencing.   In Structured FrameMaker, on its own, this works just fine; it all fell flat on its face when trying to import xml.   I tried to see whether the xref element's ID attribute could also be a UniqueID, but as just about everyone has said, this is a silly idea.   I was just trying stuff to see whether it might make a difference - you'll not be surprised to see that it didn't!
For the moment, I have attributes called ID with a value of IDReference, and I understand you're all suggesting to leave it at that.
If I understand correctly, I could eventually use an IDRef attribute if I wanted a UniqueID value to be used, though I'm not sure what a UniqueID is used or useful for, so will file that for future use.
Again, thanks for the advice and help.
Chris