The CANCEL SOURCE command cancels the source file directory
    search list established with a previous SET SOURCE command. After
    the directory search list is canceled, PCA is unable to find any
    source file which has been moved or copied since being compiled.

    If you have established a directory search list for a specific
    module with the SET SOURCE/MODULE=modname command, you must use
    the same /MODULE qualifier on the CANCEL SOURCE command to cancel
    that search list.

    If you have established a directory search list for the EDIT
    command using the SET SOURCE/EDIT command, you must use the
    same /EDIT qualifier on the CANCEL SOURCE command to cancel that
    search list.