Part Modeling > Datum Features > Datum Planes > About Creating a Datum Plane Using a Datum Coordinate System
  
About Creating a Datum Plane Using a Datum Coordinate System
You can select a datum coordinate system as a placement reference and place the datum plane along one of its axes, at an offset from the origin, or through one of the virtual planes. The constraints that are available are Offset and Through. Offset is the default.
When the constraint type is Offset, the datum plane is placed along one of the axes of the datum coordinate system that is selected as a placement reference and is offset from the origin.
If you set the show_dim_sign configuration option to no, the offset dimension is displayed as an absolute or positive value even if you have entered a negative value, and the datum plane flips to the opposite side of the reference datum coordinate system. When you set show_dim_sign to yes with a negative value, the offset dimension is displayed as the real value, and the datum plane retains its location on the same side as the reference datum coordinate system.
When the constraint type is Through, you must select one of the following virtual planes defined by the selected datum coordinate system:
xy
yz
zx
The default virtual plane is yz. The datum plane is defined through the specified axes and placed through the selected virtual plane of the datum coordinate system. That is, if you select the xy-virtual plane, the datum plane is defined through the x- and y-axes of the datum coordinate system.