NX Where do NX threads standard come from?

 What are NX thread standards based on?

While at one time the thread data was taken from the Machinery Handbook, per the NX2206 documentation and Development, that is no longer the case.

Per the NX2206 documentation:

https://docs.sw.siemens.com/en-US/doc/209349590/PL20200605195244930.modeling/hole_adv_hole_feat_col_names

There is no single industry standard used to define the data tables for threaded hole features, as there is with the older symbolic Thread lookup tables. The standard data tables for the newer threaded hole come from multiple standards, catalogs, and best practices, some of which do not specify all parameters of each feature or not the full range of sizes, but are inferred from other standards of similar design. There are also some standards that specify dimensions for tap drills that do not correspond to any real standard drilling tool. In those instances, the best standard size is used instead.

You can customize these data tables as required. For more information, see Customize standard data tables for Hole features.