168:/lib/no_skill_decay.c (/lib/no_skill_decay.c)
(public int) nsd_hook_unknown_skill(string str)
/*
 * Function name: nsd_hook_unknown_skill
 * Description  : The skill the player tries to retrain is not known.
 * Returns      : int 1/0 - 0 for notify_fail, 1 for write.
 */
