[dita] Link text and key references

Hi all,

I'm still new here, so I apologize in advance if I'm either questioning
closed issues or missing something in the spec.

I'm trying to determine if it's possible to override the visible text
within various key referencing tags, specifically xref, using a key
defining topicref, and I'm having trouble figuring it out based on the
spec.  The section "Key-based (indirect) addressing"
(archSpec/keyref.dita) says the following:

====
When a key definition has a