NX Meaning of the symbol "6H" displayed in "hole and threading callout"

When inserting PMI "Hole and Thread Callout" dimensions, "6H" is displayed in the dimension string. What does this mean?

Reproduced Steps:

1. Create Threaded Hole or Thread

2. PMI > Hole and Thread Callout PMI

3. Select the created dimension > Mouse right crick > Settings

Represents the thread accuracy grade

6H : Internal(Metric)

6g : External(Metric)

2B : Internal(Inch)

2A : External(Inch)

Metric thread tolerance has been supported from NX 2206 so that they can be displayed when entering dimensions.

In NX 1899 - 2007, all thread tolerance (2A, 2B) are displayed regardless of metric or inch. It's not correct as the metric value, but NX is designed to display it. Its value cannot be changed, but it can be hidden.

In addition, we used to call it "Internal/external thread symbol" instead of "thread tolerance".

***Please refer to PL8709320 for Japanese article.