Thank you, Gwendolyne, that worked like a charm!
In order to streamline my workflow I modified a bit that routine to make it generate also the spell file name, apart from the spell name and the spell description. I attach the generated file to illustrate what I'm doing. My goal is to use just string references, rather than string literals, in my tp2 file. This is what I want to do:
COPY_EXISTING @100001 ~override~ SAY NAME1 @100002 SAY UNIDENTIFIED_DESC @100003
Here, @100001 would be something like SPWI201.spl. However, it looks like doing this breaks some syntax rule, WeiDU complains about that @100001 reference. I attach the debug file with the error. What am I doing wrong?