Oracle Data Guard platform compatibility

There is two interesting MOS notes about Oracle's DR solution (DG).
- Data Guard Support for Heterogeneous Primary and Physical Standbys in Same Data Guard Configuration [ID 413484.1]
and
- Data Guard Support for Heterogeneous Primary and Logical Standbys in Same Data Guard Configuration [ID 1085687.1]
It seems that we have not so much opportunities to implement heterogeneous DR configurations.