This is the Dtk_AxisSystem class.
A Dtk_AxisSystem is an additional orthogonal basis with a name and an associated Dtk_transfo. 
Use IsDefault method to find the default placement used in a part. 
If you need to see an entity in one of the additional basis of a file you can use a Transform method. 
 A Dtk_AxisSystem contains the AxisSystem definition which is defined by its name, status and a matrix
This class lets you use Dtk_AxisSystem.