ServiceConditions resource URI and Mandatory URI's

The specification intentionally does not call out mandatory URIs beyond the service root URI; the ServiceRoot schema does specify the SessionService as mandatory simply out of need to support the "shall" requirement in the specification for supporting Redfish sessions. Beyond this, the data model is optional to implement due to varying product requirements and customer expectations for different classes of devices. Redfish as a standard does not dictate management requirements since DMTF does not produce products.

However, URI requirements come into play when you need to start conforming to a Redfish profile; organizations, like OCP, create Redfish profiles as a way to enforce conformance to management requirements, which would include mandatory URIs. For example, in order to be accepted as an OCP server, you need to conform to OCP's Redfish server profile, which does specify some mandatory URIs.