Will make proposal with suggested syntax. Degrees is my main interest, but we can leave space for other stuff.

Came about recently (as well as longer ago) when discussing here:
RobotLocomotion/drake#13036 (review)

Steps:

• New pose proposal: support rotation in degrees (#252) #589 Baseline support for //pose[@rotation_type]
• Ensure proposal is synchronized with conclusion from discussion in #589 Update document to better reflect proposed and accepted implementations sdf_tutorials#56
• Support for snap-to conversion with ign sdf Support printing sdf poses in degrees and allow snapping to commonly used angles #689
• Empty pose not interpreted as identity when rotation_format=quat_xyzw is set #707
  Relates: origin: Support degrees in rpy ros/urdfdom#124

(Moved from gazebosim/sdf_tutorials#8)