A Dtk_FeaturePtr can be construction or manufacturing feature see class info: Dtk_feat. It can be associated with any Dtk_Node type. Until now, Feature read is only available in CatiaV5, CatiaV6, UG NX, Solidworks and ProE/Creo Parametric libraries and needs a specific licence.
See Feature mapping in readers menu :

readers
Sample to write a Dtk_Feature