The File Scan routine searches an area, such as a directory, for
    all files matching the file specification given and transfers
    program execution to the specified user-written routine.
    Wildcards are acceptable. An action routine is called for each
    file and/or error found. LIB$FILE_SCAN allows the search sequence
    to continue even if an error occurs while processing a particular
    file.

    Format

      LIB$FILE_SCAN  fab ,user-success-procedure

                     ,user-error-procedure [,context]