If you want to add an audit trail of the modifications made to a critical field named "PRIORITY" it can be done with the following:
1) Create a duplicate "PRIORITY" field (named "PRIORITYDelta") that is hidden and has in its input translation formula a statement to store the contents of the PRIORITY field. This will retain the contents of the priority field before editing in a current session.
2) Create a multi-value field ("Updatesto") with a formula that compares PRIORITY to PRIORITYDelta when the document is being saved and when the condition is right (i.e. PRIORITY != PRIORITYDelta) attaches the new save information to the field:
feed := @Name([CN]; @V3UserName) + " on " + @Text(@Date(@Now)) + " at " + @Text(@Time(@Now)) + " " + PRIORITY; FIELD Updatesto := @If(@IsDocBeingSaved & PRIORITY != PRIORITYDelta ; Updatesto : feed; Updatesto); Updatesto
Note that the Revision field (Updatesto) needs to before PRIORITYDelta Field on the form for the revision field to keep a change history.