Different type of tracing. I'm referring to textual tags which are used to associate a design requirement with a piece of code, the idea being that you can show a requirement is fulfilled by showing that it traces to tests and code, and that the existence of any piece of code needs to be justified by tracing back to the requirements.

http://en.wikipedia.org/wiki/Requirements_traceability

Borland's Caliber was once popular for requirements traceability, http://www.borland.com/Products/Requirements-Management/Cali...

Caliber looks great. I can only hope they're using something like that nowadays. Of course it has the word "Agile" in it so it's probably about 10 years too young.

Different type of tracing. This is basically tracing line items from a document to another set of line items on lower level documents, potentially all the way down to specific lines of source code.

Jinx!