HL7 version implemented

Question: In FAQ section, the answer to “What technologies is OpenMRS built on?” says the form data is converted into HL7 before going into the database. Can you please tell me what specific HL7 version is used for this?

HL7 version 2.5 but this was mostly used by the formentry module which is getting retired. https://wiki.openmrs.org/display/docs/FormEntry+Module

FWIW, we are moving to FHIR https://wiki.openmrs.org/display/projects/OpenMRS+FHIR+Module