Ok, I should clarify a bit. The label is only the number of the tree's tag (no preceeding text, "TREE#" or anything). The issue i have with using the actual point number is very often, I am using points provided by others and the point number does not matcg the tag number. Or the tag numbers are not in a logical order or even completely sequential. I was looking for a simple way to add sequential tag numbers to the description to ease the labeling. I use the "TREE" part with description keys to manage the styles used.
That said, I am not familiar with the XDREF you suggest (my use of C3D is admittedly limeted).