A program name is considered explicit if you specify the program's full filename including its extension in the call. For example:
CALL "abc.gnt" USING ....
This forces the run-time system to look for the exact filename that you specify, in this case abc.gnt. If the file is not located, a "program not found" error message is issued.
Additionally, you can specify the exact location of the program to be called, by qualifying the program call with a PC drive-letter or pathname. For example, to look in the directory c:\programs for the program abc.gnt, use the statement:
CALL "c:\programs\abc.gnt" USING ....
Note, however, that specifying the drive or pathname is not recommended, as unexpected results can occur where the referenced module exists in more than one file, or type of format, or if the application is ported to other environments.
Specifying the program extension in a call is not recommended.