A datum is a geometric point of reference, such as a plane or an axis. Datums are used as points of comparison between test and reference objects. The choices at Tools > Datums are:
Create Datums - To
create a datum is to draw it by a variety of geometric methods and assign
a name to it so that it can be referenced by other tools.
Modify Datum Display ... - presents a set of graphic display options that apply to the currently selected datum.
Copy Datums - allows one or more datums to be copied between objects in the current model.
Toggle All Datums
- (or Alt-7) causes all datums on the current object to appear or disappear
from view.
Toggle Datum Planes
- toggles the visibility of all plane datums on the current object.
Toggle Datum Axes
- toggles the visibility of all axis datums on all visible objects.
Toggle Datum Points
- toggles the visibility of all point datums on all visible objects.
Toggle Datum Targets
- toggles the visibility of all target datums on all visible objects.
Toggle Labels - switches the display of datum name labels on and off.