NX What are N and T axes that appears when creating a sketch "On path"?

What are N/T axes that appears when creating a sketch "On path"?
And how can we control it?

Solution

N->Stands for Normal axis
T->Stands for Tangent axis.
 
This is primarily designed when the user selects a face edge as the path.
T is usually tangent to the face and N axis is normal to the face.
The users don't have a control over these axes 

Hardware/Software Configuration

Platform: INTL64
OS: windows
OS Version: 1064
Product: NX
Application: DESIGN
Version: V12.0.2
Function: SKETCHER

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