Obligations are a mean offered by HL7 FHIR to specify functional capabilities that defined actors may, should or shall apply to the data elements specified by the profiles.

Should be: Obligations are a means offered by HL7 FHIR to specify functional capabilities that defined actors MAY, SHOULD or SHALL apply to the data elements specified by the profiles.

The current choice has been that of defining the obligation in StructureDefinitions distict form those used for defining the strcutural constraints.

should be: The current choice has been that of defining the obligation in StructureDefinitions distict from those used for defining the structural constraints.