To date, schemas describing Rubin data products have been described in the DPDD. The DPDD is a project-level change controlled document. This means that simple changes to columns require project approval, which is cumbersome when we want to say, just change the name of a column in the database. It also makes the DPDD large and not very user friendly.
Science Data Model schema definitions for all Rubin data products are now described in YAML files that are version controlled in the cat package: https://github.com/lsst/cat/ . The baseline schema in LDM-153 is autogenerated from the cat package. The cat package now serves as the "source of truth" for the schema for all Rubin data products.
The DPDD should not duplicate information in LDM-153 however there is still a need for some form of user facing scientific description of the data products. The content and focus of the DPDD needs to be rethought by the DM Science team