When using this key combo in edit mode with a face selected the following options are presented in the mesh tools panel or by pressing F6:
- Rotation axis. The axis around which the face is to be rotated.
- Constraint axis. The axis the vertices are allowed to move in.
- Rotation point. The point of the face to rotate around.
- Degrees. The degrees of rotation.
Hope it's useful.
Star Shape Extrusion