While in a Sketch, a datum axis is unable to be selected while creating a
Horizontal, Vertical, or Parallel dimension.
Solution
If a Sketch dimension needs to be associated to a datum axis, use the 'Inferred
Dimension' command instead.
The reason why a datum axis cannot be selected for a Horizontal, Vertical, or
Parallel dimension is because these dimension types are point-to-point
dimensions. Datum Axes in NX do not have a user-visible point.
Notes and References
Hardware/Software Configuration
Platform: all
OS: n/a
OS Version: n/a
Product: NX
Application: DESIGN
Version: V7.5
Function: SKETCHER
Ref: 001-6832631