Make the field itself a button. Clicking on the field would run the following script:
If (YourField = "")
SetField (YourField ; Get(CurrentTimeStamp) )
If the field is blank, it will get timestamped. If it has a value, the script will do nothing. And the field being a button will prohibit manual entry.
NOTE: Make sure the field is not in your tab order so it cannot be tabbed to.
change the behavior of that field to not allow to be entered in Browse Mode
awesome, thank you very much for all of your help.