Connection between HL7 and LOINC

HI ,All…i want to clear the difference between these topics:-

1.How LOINC and HL7 V3 are different from each other??

2.HOw LOINC and OID’s are differ from each other??

3.Is there any common thing among HL7 and LOINC?

4.LOINC standard is worldwide standard so if i follow these codes then my software will be able to exchange data with any other software?

Thanks for the questions. Most of the answers can be found in the LOINC Users’ Guide (the definitive documentation for LOINC). In short, LOINC is a vocabulary standard for clinical and laboratory observations (e.g. tests and measurements), whereas HL7 is a standard for clinical messages. LOINC is designed to work in conjunction with HL7 (i.e. LOINC codes should be used in the OBX-3 “Observation Identifier” field of the OBX segment of an ORU HL7 message.

OIDs identify a set of things much broader than what is encompassed by LOINC. See a brief intro to how OIDs in relation to their use in HL7 here: For example, there is an OID to identify LOINC as a whole coding system from which concepts are drawn to use within HL7 messages.