Towards the goal of centralizing normative requirements and ensuring internal consistency – Remove all four variations of MAY be a UUID from: https://build.fhir.org/ig/HL7/fhircast-docs/2-4-Subscribing.html . Specifically:   >The identifier of the session that the subscriber wishes to subscribe to or unsubscribe from. MAY be a Universally Unique Identifier ( UUID ). https://build.fhir.org/ig/HL7/fhircast-docs/2-4-Subscribing.html#subscription-request   >The topic given in the corresponding subscription request. MAY be a UUID. https://build.fhir.org/ig/HL7/fhircast-docs/2-4-Subscribing.html#subscription-denial   >The identifier of the session that the subscriber wishes to subscribe to or unsubscribe from. MAY be a UUID. https://build.fhir.org/ig/HL7/fhircast-docs/2-4-Subscribing.html#unsubscribe   >The session topic given in the corresponding subscription request. MAY be a UUID. https://build.fhir.org/ig/HL7/fhircast-docs/2-4-Subscribing.html#subscription-confirmation