17. ABS-GEN-NO (halfword binary).

(ABSOLUTE-GENERATION-NUMBER) The absolute generation number of the table for which a GD command was issued. This field will be zero if the table has never been stored. For more information see Generations.

In version 5, when an alternate index is defined in memory only, the GD command showed the number of generations as 0; starting with Version 6, the number of generations is shown as 1.