To specify that the values in the SRTSEQ and LANGID command parameters or control specification keywords should be used to determine the alternate collating sequence, specify ALTSEQ(*EXT) on the control specification. For example, if ALTSEQ(*EXT) is used, and SRTSEQ(*LANGIDSHR) and LANGID(*JOBRUN) are specified, then when the program is run, the shared-weight table for the user running the program will be used as the alternate collating sequence.
Since the LOOKUP and SORTA operations are affected by the alternate collating sequence when ALTSEQ(*EXT) is specified, character compile-time arrays and tables are sequence-checked using the alternate collating sequence. If the actual collating sequence is not known until runtime, the array and table sequence cannot be checked until runtime. This means that you could get a runtime error saying that a compile-time array or table is out of sequence.
Pre-run arrays and tables are also sequence-checked using the alternate collating sequence when ALTSEQ(*EXT) is specified.