You can only purge an activity slip if the invoice on which it was billed has already been purged. Also, if you include activity slip hours on timesheets, you can only purge an activity slip if the timesheet on which it was included has already been purged.
If you only want to purge activity slips for the employees and vendors who have been assigned particular identifier codes, enter the relevant codes in this field. The activity slips of the employees and vendors who have been assigned ALL the identifiers that you enter here will be purged.