My literature for Square D's Micro 1 hand-held (made by Idec) shows:
Internal relays: 400 to 597; ordinarily cleared when power is cycled, but can be designated as retentive - see FUN6
Special internal relays 600 to 717 - most of these are not used, but 690 to 717 have dedicated functions (i.e. 714 is the 1sec internal clock pulse).