It is possible to use SE16 to determine the name of a SmartForm form used by a specific message type. In SE16, view the table TNAPR and make your selection criteria. I normally pick my output type (KSCHL = ZLnn), and my application (KAPPL = V2 for Shipping or V6 for Handling Units). Once you hit F8, you will see the list of results. Under the column "Form name" (SFORM), you will see the name of the SmartForm used for the desired label or output type.