PaNOSC and ExPaNDS H2020 projects are developing data management and analysis services for the photon and neutron user community. These services will be available first locally, and in the future via the EOSC. To help as large a user community as possible, PaNOSC has launched a Call for Use Cases for the data management services being developed. Anyone who is a user of one of the photon and neutron facilities, either directly or via open data from one of these facilities, is encouraged to submit their use case(s) for data treatment or data management needs. The Use Cases must be related to one of the data services being developed by PaNOSC (see https://www.panosc.eu/services/) and ExPaNDS.