As part of fixing the missing text in links in MIDD17, I tested and fixed the system for implementing links from one document to a fragment of another. This is basically how it works:

If you want to link from one document (say MIDD17) to another (say TRIU1), you can link to the whole document using mol:TRIU. However, sometimes you might want to link to a specific part of the TRIU1 document (which is a multi-text document). You can link to a specific <div> in the target document like this:

• First, give the <div> in the target document its own @xml:id. For instance, we might want to link to the "Grocer's Company" section of the TRIU1 document, so we find the div that contains that section, and give it an @xml:id. Our convention is that an @xml:id for a section in a target document should be created with a prefix that consists of the main document id (TRIU1) and an underscore. So we do this: <div xml:id="TRIU1_grocers">.
• In the document where you want to put the link, construct the link as follows: <ref target="mol:TRIU1#TRIU1_grocers">. In other words, mol: + the document id + # + the div id.

Links constructed like this are now working on the site (see MIDD17 links to TRIU1 for examples).