FYI: HL7 dropped the "D" from DSTU to get STU. The old was "Draft Standard for Trial Use", which people pointed out includes both he word "Draft", and also "Trial Use". This was discussed as redundant. The word "Draft" also left people believing that the specification was Pre-Ballot. Yet what they have has gone through many formal and informal ballot processes Further IHE profiles at this stage of maturity are listed as "Trial Use". So the next ballot and the result of that ballot will be called "Standard for Trial Use" - STU.
IHE will likely also need to get these 'profiles' integrated into the new FHIR registry of Profiles. This is an evolving thing right now, but I predict that soon there will be a registry and publication mechanism available where these IHE profiles could be published more visible to the FHIR community - See FHIR Foundation. Right now, there are no FHIR StructureDefinition for these as these profiles don't constrain FHIR by much, and they are written so that the IHE actors are robust to the FHIR resources not being constrained at all. This is an intermediate step, not a long term strategy. Long term needs to fit into the FHIR ImplementationGuide and conformance -- See Grahame's blog today on how Profiles fit within Conformance.