1. Put a Sphere SOP and set it to any polygon mode. 2. Select couple polygons and call TransformSOP in viewport.
After accepting selection we end up with a handle locally aligned to geometry where selection was made. Now RMB on a handle and select Handle Parameters, which will open small window.
I want to know can I get access to Handle Rotation there. Where I should look for it? Is this data part of the SOP?
Ideally I would like to get this data and output it as second operator output, since it looks that we finally can create operators with many outputs.
No, the local orientation data is part of the handle/PI, not the operator node. Accessing private handle data like this is not really something that's appropriate during a node cook.
Unfortunately, I don't think the code for computing the local frames is even exported to the HDK.