Document in one place the specific minimal set of work that would be required to fully replace the PDAC Portal's image-search features with an IVOA-services-oriented equivalent. This was in-progress work at the time of the DM-10 freeze, and is the minimal piece of new development that would facilitate the use of the Portal during DP0 and commissioning activities.

This amounts to writing a specification for DM-18692, and involves collecting various sketches together for concreteness.