A version of the Science Platform Design document, LDM-542, is ready for submission to the DM change control process.

It is available for now at https://ldm-542.lsst.io/v/DM-13838/index.html (I'll consult with Tim Jenness about whether/how to create an RFC branch in the repository).

This is largely the version used in the DM review last year, with some clarifications to issues that have been refined at the LSP workshop and since. Further changes can be expected, but we need to establish this baseline now.