Source files for external cards are registered in the repository as Control Cards files, and must be named as follows, where .srt is the default file extension:
//SYSIN DD DSN=MY.SORTCARDS.LIB.FILE1
the source file name must be MY.SORTCARDS.LIB.FILE1.srt.
//SYSIN DD DSN=MY.SORTCARDS.LIB(FILE2)
the source file name must be MY.SORTCARDS.LIB(FILE2).srt, or if the member name is unique, FILE2.srt.
//SYSIN DD DSN=MY.SORTCARDS.LIB.FILE3(+1)
the source file name must be MY.SORTCARDS.LIB.FILE3.srt, without the generation number.