This case-sensitive code system http://hl7.org/fhir/us/ndh/CodeSystem/EndpointConnectionTypeCS defines the following codes:

Code	Display	Definition
hl7-fhir-opn	HL7 FHIR Operation	Interact with a FHIR server interface using FHIR's RESTful interface using an operation other than messaging. For details on its version/capabilities you should connect the value in Endpoint.address and retrieve the FHIR CapabilityStatement.
rest-non-fhir	REST (not FHIR)	Interact with a server using HTTP/REST but not FHIR. Should be used for web portals.
ihe-xcpd	IHE XCPD	IHE Cross Community Patient Discovery Profile (XCPD) - http://wiki.ihe.net/index.php/Cross-Community_Patient_Discovery
ihe-xca	IHE XCA	IHE Cross Community Access Profile (XCA) - http://wiki.ihe.net/index.php/Cross-Community_Access
ihe-xdr	IHE XDR	IHE Cross-Enterprise Document Reliable Exchange (XDR) - http://wiki.ihe.net/index.php/Cross-enterprise_Document_Reliable_Interchange
ihe-xds	IHE XDS	IHE Cross-Enterprise Document Sharing (XDS) - http://wiki.ihe.net/index.php/Cross-Enterprise_Document_Sharing
ihe-iid	IHE IID	IHE Invoke Image Display (IID) - http://wiki.ihe.net/index.php/Invoke_Image_Display
ihe-pdq	IHE PDQ	IHE Patient Demographics Query (PDQ) - http://wiki.ihe.net/index.php/Patient_Demographics_Query
ihe-pix	IHE PIX	IHE Patient Identity Feed (PIX) - http://wiki.ihe.net/index.php/Patient_Identity_Feed
ihe-mhd	IHE MHD	IHE Mobile Healthcare (MHD) - http://wiki.ihe.net/index.php/Mobile_Healthcare