To Create a Datum Identifier Symbol With a Surface Indication Line (AutoCAD Mechanical Toolset)

Click Annotate tabSymbol panelDatum Identifier. Find
Select an object to attach the datum identifier to.
At the command prompt, enter F.
Note:
The surface option is available only if the revision of the standard in use permits surface indication lines
Specify the start point of the surface indication line. (1 in the illustration above).
Specify one or more points to define the vertices of the leader (2,3 and 4 in the illustration above), and then press ENTER.
In the Datum Identifier dialog box, enter the data.
Click OK.