Attaching a Datum Identifier Symbol to an Entity To attach a datum identifier symbol to an entity: Do one of the following: On the ribbon, select Mechanical Annotate > Symbols > Datum Identifier > Create. On the menu, click Mechanical Annotate > Symbols > Datum Identifier > Create. Type AM_DatumIdentifier. In the graphics area, specify an entity to attach the datum identifier symbol to. When you select the extension line of a linear dimension, the datum identifier symbol appears. It appears on the extension line at the point where the dimension line touches the extension line. The triangle of the datum identifier symbol appears on the reference geometry at the specified point. Specify the start point for the leader. Specify one or more points to define other segments of the leader line and press Enter. In the dialog box, specify the identifier letter for the symbol and click OK. Parent topicDatum Identifier Symbols