Code-system identities

resolveSystem knows these code systems by name. Each row is one identity, bundled as SYSTEM_IDENTITIES: the canonical URI the engine treats as the system, its OID, and the mnemonics it accepts. URIs and mnemonics are matched in any letter case; an OID is accepted bare or with the urn:oid: prefix.

Name	Canonical URI	OID	Mnemonics
LOINC	http://loinc.org	2.16.840.1.113883.6.1	LN, LOINC
SNOMED CT	http://snomed.info/sct	2.16.840.1.113883.6.96	SCT, SNOMEDCT, SNOMED
ICD-10-CM	http://hl7.org/fhir/sid/icd-10-cm	2.16.840.1.113883.6.90	I10C, ICD10CM
RxNorm	http://www.nlm.nih.gov/research/umls/rxnorm	2.16.840.1.113883.6.88	RXNORM
UCUM	http://unitsofmeasure.org	2.16.840.1.113883.6.8	UCUM
CPT	http://www.ama-assn.org/go/cpt	2.16.840.1.113883.6.12	C4, CPT
NDC	http://hl7.org/fhir/sid/ndc	2.16.840.1.113883.6.69	NDC
CVX (CDC Vaccine Codes)	http://hl7.org/fhir/sid/cvx	2.16.840.1.113883.12.292	CVX

The URIs and OIDs come from the FHIR R4 terminology-systems registry and its ICD page. The HL7 table 0396 mnemonics are LN, SCT, I10C, RXNORM, UCUM, C4, NDC and CVX; the others (LOINC, SNOMEDCT, SNOMED, ICD10CM and CPT) are accepted short aliases, not table 0396 codes. ICD-9-CM and ICD-10-PCS are not listed: their OIDs could not be pinned to one primary source, so they are left out rather than guessed. The crosswalk resolvers still name ICD-9-CM by its URI, http://hl7.org/fhir/sid/icd-9-cm (ICD9CM_SYSTEM).

HL7 v2 tables

HL7 v2 tables are resolved by pattern, not listed:

Form	Pattern	Example
URI	http://terminology.hl7.org/CodeSystem/v2- + table	http://terminology.hl7.org/CodeSystem/v2-0203
OID	2.16.840.1.113883.12. + table	2.16.840.1.113883.12.203

The table number is one to four digits: zero-padded to four in the URI, without leading zeros in the OID. Either form resolves to an identity whose URI, OID and mnemonic (v2-0203) are built from the table number. The mnemonic is not accepted as input on its own.

Reference

• resolveSystem and SYSTEM_IDENTITIES
• HL7_V2_OID_ROOT and HL7_V2_URL_PREFIX
• ICD9CM_SYSTEM, ICD10CM_SYSTEM, SNOMEDCT_SYSTEM and RXNORM_SYSTEM
• How to use it: resolve a code system