When you select the drafting standard, the default settings for datum identifier symbols and feature identifier symbols change to match that drafting standard.
If necessary, you can customize these settings to suit your drafting requirements.
You cannot change settings of datum identifier symbols independently of feature identifier symbols. Both symbols derive their settings from the same set of configuration parameters. The only configurable options available for these symbols are the text and leader settings.
Because text and leader lines are the most common objects used for annotations, AutoCAD Mechanical toolset provides a single configuration point (the Standard Settings dialog box) enabling you to specify their default properties. These settings are the master settings.
In the Datum And Feature identifier Settings dialog box, the text and leader settings default to “By NameOfCurrentDraftingStandard.” If you modify the master settings, datum and feature identifier symbols automatically acquire the new settings. However, if you do not want datum and feature identifier symbols to follow the master settings, you can override the text height and select a specific value.