The practice is that every domain committee can decide to elevate extensions into the extension pack. FHIR-I owns the pack. The process is to propose an extension to the relevant working group. If there are questions about whether or not an extension is inappropriate, FHIR-I would bring to FMG. Extensions that apply to any resource type are typically maintained by FHIR-I as infrastructure considerations. Agree, that it would be useful to document this but it should be Confluence documentation rather than specification documentation. We will document the criteria in the governance in Confluence and reference from the IG.