This is a cross-post from ROS Discourse. Taking the main content from that post, but scrubbing most links (due to two-link limit for new users):
I am robotics software developer for Toyota Research Institute, part of the team working towards robust manipulation. For the past few months, I have been working with @scpeters and @azeey at OSRC to start improving the documentation for the full specification for SDFormat. We are using this as a launching point to extend SDFormat with a proposal for pose frame semantics, which aims to improve expressivity by enabling the definition of arbitrary coordinate frames within a model and choosing the frame relative to which each frame is defined. This is something that I, as part of TRI, would like for Drake, and something that we hope is useful for the ROS and Gazebo communities.