<status value="active"/> <experimental value="false"/> <publisher value="FHIR Project team"/> <contact> <telecom> <system value="url"/> <value value="http://hl7.org/fhir"/> </telecom> </contact> <description value="This value set defines the ISO 3166 Part 1 3-letter codes"/> <compose> <include> <system value="urn:iso:std:iso:3166"/> <filter> <property value="code"/> <op value="regex"/> <value value="[A-Z]{3}"/> </filter> </include> </compose> </ValueSet>

Include codes from urn:iso:std:iso:3166 where code matches (by regex) [A-Z]{3}