NX What is the difference between "Screw Size" and "Shaft Diameter" in NX_Thread_Standard.xml file

NX_Thread_Standard.xml has "Screw Size", "Shaft Diameter" columns with Values.

What is the difference between "Screw Size" and "Shaft Diameter”?

In Thread command "Thread Size" uses the "Size" from NX_Thread_Standard.xml.

The ‘ScrewSize’ value in the ‘NX_Thread_Standard.xml’ file is not used in the Threaded Hole feature itself; it simply indicates (but does not determine) which entry in the ‘NX_Screw_Clearance_Hole_Standard.xml’ will be used if the ‘Threaded Hole’ feature is changed to a ‘Simple – Screw Clearance’ hole.

(You may have noticed that the ‘ScrewSize’ values in the ‘NX_Thread_Standard.xml’ file correspond to the ‘Size’ values in the ‘NX_Screw_Clearance_Hole_Standard.xml.)

Note that it is the ‘TapDrillDia’ of the threaded hole that determines which Screw Clearance Hole size will be used by default, using the entry with closest ‘HoleDiameter’ entry.