A Feature (pointer on Dtk_feat) can be a construction or a manufacturing feature.
Parameters can be used in downstream applications (holes, patterns, threads, pockets and others depending on the CAD format).
It can be associated with any Dtk_Node type in the construction tree.
Feature read is only available from :

CATIA V5
CATIA V6
UG NX
SOLIDWORKS
Creo Parametric (Pro/Engineer)
Feature reading needs a specific licence.
All metric data in feature classes are given in millimeters (MM).
All angular data are given in degree.

See Feature mapping in readers menu :
Readers Mapping