{STOP: Message}
This action is only valid in preupdate rules. This will interrupt the processing of preupdate rules and returns to the user without executing further rules. This action works differently from the ERROR action in that the ERROR action continues execution and may accumulate more than one message.
You may use the standard escape characters in the error message. The most common requirement is to use \n as a linefeed within your message.
Also, you may obtain the value of any field on the form and insert this into the message. This is achieved by using the form $$FIELDNAME$$ into the message. $$FIELDNAME$$ is replaced with the current value of the field.