The following six macros all resolve to a file specification (or possibly several file specifications for $** and $?):
$* $@ $** $< $? $$@
You can append characters to any of these macros to modify the file name returned by the macro. Depending on which character you use, parts of the full file specification are returned:
Appended Character File Part Returned D F B R File Path Yes No No Yes Base File Name No Yes Yes Yes File Name Extension No Yes No No