Update on our suggestion "that a Map should be included in the LOINC extension, in addition to alt identifiers. This will enable terminology servers to translate back and forth between LOINC and SNOMED CT codes in the existing standard way."
Previously we added the following warning in the ECL guide in the alternate identifiers section:
- ECL is always evaluated against SNOMED CT concepts. When you run a query using alternate identifiers from another code system only concepts that are in the SNOMED CT representation of that other code system will be returned. For example the descendants of a concept in the SNOMED CT version of a code system is likely to be different from the code system of the alternate identifier.