> For the complete documentation index, see [llms.txt](https://docs.snomed.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.snomed.org/snomed-ct-specifications/snomed-ct-expression-constraint-language/design/5-syntax-specification/long-syntax.md). # Long Syntax The following ABNF definition specifies the Long Syntax the SNOMED CT Expression Constraint Language. Please note that all keywords are case insensitive.\ This ABNF syntax and the ANTLR syntax is maintained in the [SNOMED Expression Constraint Language GitHub](https://github.com/IHTSDO/snomed-expression-constraint-language) repository. {% code title="ECL 2.3 - Long Syntax" overflow="wrap" lineNumbers="true" fullWidth="true" %} ```abnf expressionConstraint = ws ( refinedExpressionConstraint / compoundExpressionConstraint / dottedExpressionConstraint / subExpressionConstraint ) ws refinedExpressionConstraint = subExpressionConstraint ws ":" ws eclRefinement compoundExpressionConstraint = conjunctionExpressionConstraint / disjunctionExpressionConstraint / exclusionExpressionConstraint conjunctionExpressionConstraint = subExpressionConstraint 1*(ws conjunction ws subExpressionConstraint) disjunctionExpressionConstraint = subExpressionConstraint 1*(ws disjunction ws subExpressionConstraint) exclusionExpressionConstraint = subExpressionConstraint ws exclusion ws subExpressionConstraint dottedExpressionConstraint = subExpressionConstraint 1*(ws dottedExpressionAttribute) dottedExpressionAttribute = dot ws eclAttributeName subExpressionConstraint = [constraintOperator ws] ( ( [refsetOperator ws] (eclFocusConcept / "(" ws expressionConstraint ws ")") *(ws memberFilterConstraint)) / (eclFocusConcept / "(" ws expressionConstraint ws ")") ) *(ws (descriptionFilterConstraint / conceptFilterConstraint)) [ws historySupplement] eclFocusConcept = eclConceptReference / wildCard / altIdentifier dot = "." refsetOperator = memberOf / refsetContainingAny memberOf = ( "^" / ("m"/"M") ("e"/"E") ("m"/"M") ("b"/"B") ("e"/"E") ("r"/"R") ("o"/"O") ("f"/"F") ) [ ws "[" ws (refsetFieldNameSet / wildCard) ws "]" ] refsetContainingAny = "^R" / ( ("r"/"R") ("e"/"E") ("f"/"F") ("s"/"S") ("e"/"E") ("t"/"T") ("c"/"C") ("o"/"O") ("n"/"N") ("t"/"T") ("a"/"A") ("i"/"I") ("n"/"N") ("i"/"I") ("n"/"N") ("g"/"G") ("a"/"A") ("n"/"N") ("y"/"Y") ) refsetFieldNameSet = refsetFieldName *( ws "," ws refsetFieldName ) refsetFieldName = 1*alpha eclConceptReference = conceptId [ws "|" ws term ws "|"] eclConceptReferenceSet = "(" ws eclConceptReference 1*(mws eclConceptReference) ws ")" conceptId = sctId term = 1*nonwsNonPipe *( 1*SP 1*nonwsNonPipe ) altIdentifier = (QM altIdentifierSchemeAlias "#" altIdentifierCodeWithinQuotes QM / altIdentifierSchemeAlias "#" altIdentifierCodeWithoutQuotes) [ws "|" ws term ws "|"] altIdentifierSchemeAlias = alpha *(dash / alpha / integerValue) altIdentifierCodeWithinQuotes = 1*anyNonEscapedChar altIdentifierCodeWithoutQuotes = 1*(alpha / digit / dash / "." / "_") wildCard = "*" / ( ("a"/"A") ("n"/"N") ("y"/"Y") ) constraintOperator = childOf / childOrSelfOf / descendantOrSelfOf / descendantOf / parentOf / parentOrSelfOf / ancestorOrSelfOf / ancestorOf / top / bottom descendantOf = "<" / ( ("d"/"D") ("e"/"E") ("s"/"S") ("c"/"C") ("e"/"E") ("n"/"N") ("d"/"D") ("a"/"A") ("n"/"N") ("t"/"T") ("o"/"O") ("f"/"F") mws ) descendantOrSelfOf = "<<" / ( ("d"/"D") ("e"/"E") ("s"/"S") ("c"/"C") ("e"/"E") ("n"/"N") ("d"/"D") ("a"/"A") ("n"/"N") ("t"/"T") ("o"/"O") ("r"/"R") ("s"/"S") ("e"/"E") ("l"/"L") ("f"/"F") ("o"/"O") ("f"/"F") mws ) childOf = "" / ( ("a"/"A") ("n"/"N") ("c"/"C") ("e"/"E") ("s"/"S") ("t"/"T") ("o"/"O") ("r"/"R") ("o"/"O") ("f"/"F") mws ) ancestorOrSelfOf = ">>" / ( ("a"/"A") ("n"/"N") ("c"/"C") ("e"/"E") ("s"/"S") ("t"/"T") ("o"/"O") ("r"/"R") ("o"/"O") ("r"/"R") ("s"/"S") ("e"/"E") ("l"/"L") ("f"/"F") ("o"/"O") ("f"/"F") mws ) parentOf = ">!" / (("p"/"P") ("a"/"A") ("r"/"R") ("e"/"E") ("n"/"N") ("t"/"T") ("o"/"O") ("f"/"F") mws ) parentOrSelfOf = ">>!" / (("p"/"P") ("a"/"A") ("r"/"R") ("e"/"E") ("n"/"N") ("t"/"T") ("o"/"O") ("r"/"R") ("s"/"S") ("e"/"E") ("l"/"L") ("f"/"F") ("o"/"O") ("f"/"F") mws ) top = "!!>" / (("t"/"T") ("o"/"O") ("p"/"P") mws ) bottom = "!!<" / (("b"/"B") ("o"/"O") ("t"/"T") ("t"/"T") ("o"/"O") ("m"/"M") mws ) conjunction = (("a"/"A") ("n"/"N") ("d"/"D") mws) / "," disjunction = ("o"/"O") ("r"/"R") mws exclusion = ("m"/"M") ("i"/"I") ("n"/"N") ("u"/"U") ("s"/"S") mws eclRefinement = subRefinement ws [conjunctionRefinementSet / disjunctionRefinementSet] conjunctionRefinementSet = 1*(ws conjunction ws subRefinement) disjunctionRefinementSet = 1*(ws disjunction ws subRefinement) subRefinement = eclAttributeSet / eclAttributeGroup / "(" ws eclRefinement ws ")" eclAttributeSet = subAttributeSet ws [conjunctionAttributeSet / disjunctionAttributeSet] conjunctionAttributeSet = 1*(ws conjunction ws subAttributeSet) disjunctionAttributeSet = 1*(ws disjunction ws subAttributeSet) subAttributeSet = eclAttribute / "(" ws eclAttributeSet ws ")" eclAttributeGroup = ["[" cardinality "]" ws] "{" ws eclAttributeSet ws "}" eclAttribute = ["[" cardinality "]" ws] [reverseFlag ws] eclAttributeName ws (expressionComparisonOperator ws subExpressionConstraint / numericComparisonOperator ws "#" numericValue / stringComparisonOperator ws (concreteString / concreteStringSet) / booleanComparisonOperator ws booleanValue) cardinality = minValue to maxValue minValue = nonNegativeIntegerValue to = ".." / (mws ("t"/"T") ("o"/"O") mws) maxValue = nonNegativeIntegerValue / many many = "*" / ( ("m"/"M") ("a"/"A") ("n"/"N") ("y"/"Y")) reverseFlag = ( ("r"/"R") ("e"/"E") ("v"/"V") ("e"/"E") ("r"/"R") ("s"/"S") ("e"/"E") ("o"/"O") ("f"/"F")) / "R" eclAttributeName = subExpressionConstraint expressionComparisonOperator = "=" / "!=" / ("n"/"N") ("o"/"O") ("t"/"T") ws "=" / "<>" numericComparisonOperator = "=" / "!=" / ("n"/"N") ("o"/"O") ("t"/"T") ws "=" / "<>" / "<=" / "<" / ">=" / ">" timeComparisonOperator = "=" / "!=" / ("n"/"N") ("o"/"O") ("t"/"T") ws "=" / "<>" / "<=" / "<" / ">=" / ">" stringComparisonOperator = "=" / "!=" / ("n"/"N") ("o"/"O") ("t"/"T") ws "=" / "<>" booleanComparisonOperator = "=" / "!=" / ("n"/"N") ("o"/"O") ("t"/"T") ws "=" / "<>" idComparisonOperator = "=" / "!=" / ("n"/"N") ("o"/"O") ("t"/"T") ws "=" / "<>" descriptionFilterConstraint = "{{" ws [ "d" / "D" ] ws descriptionFilter *(ws "," ws descriptionFilter) ws "}}" descriptionFilter = termFilter / languageFilter / typeFilter / dialectFilter / moduleFilter / effectiveTimeFilter / activeFilter / descriptionIdFilter descriptionIdFilter = descriptionIdKeyword ws idComparisonOperator ws (descriptionId / descriptionIdSet) descriptionIdKeyword = ("i"/"I") ("d"/"D") descriptionId = sctId descriptionIdSet = "(" ws descriptionId *(mws descriptionId) ws ")" termFilter = termKeyword ws stringComparisonOperator ws (typedSearchTerm / typedSearchTermSet) termKeyword = ("t"/"T") ("e"/"E") ("r"/"R") ("m"/"M") typedSearchTerm = ( [ matchKeyword ws ":" ws ] matchSearchTermSet ) / ( wild ws ":" ws wildSearchTermSet ) typedSearchTermSet = "(" ws typedSearchTerm *(mws typedSearchTerm) ws ")" concreteStringSet = "(" ws concreteString *(mws concreteString) ws ")" concreteString = QM concreteStringCharacters QM concreteStringCharacters = 1*(anyNonEscapedChar / escapedChar) wild = ("w"/"W") ("i"/"I") ("l"/"L") ("d"/"D") matchKeyword = ("m"/"M") ("a"/"A") ("t"/"T") ("c"/"C") ("h"/"H") matchSearchTerm = 1*(nonwsNonEscapedChar / escapedChar) matchSearchTermSet = QM ws matchSearchTerm *(mws matchSearchTerm) ws QM wildSearchTerm = 1*(anyNonEscapedChar / escapedWildChar) wildSearchTermSet = QM wildSearchTerm QM languageFilter = language ws booleanComparisonOperator ws (languageCode / languageCodeSet) language = ("l"/"L") ("a"/"A") ("n"/"N") ("g"/"G") ("u"/"U") ("a"/"A") ("g"/"G") ("e"/"E") languageCode = 2alpha languageCodeSet = "(" ws languageCode *(mws languageCode) ws ")" typeFilter = typeIdFilter / typeTokenFilter typeIdFilter = typeId ws booleanComparisonOperator ws (subExpressionConstraint / eclConceptReferenceSet) typeId = ("t"/"T") ("y"/"Y") ("p"/"P") ("e"/"E") ("i"/"I") ("d"/"D") typeTokenFilter = type ws booleanComparisonOperator ws (typeToken / typeTokenSet) type = ("t"/"T") ("y"/"Y") ("p"/"P") ("e"/"E") typeToken = synonym / fullySpecifiedName / definition typeTokenSet = "(" ws typeToken *(mws typeToken) ws ")" synonym = ("s"/"S") ("y"/"Y") ("n"/"N") [ ("o"/"O") ("n"/"N") ("y"/"Y") ("m"/"M") ] fullySpecifiedName = ( ("f"/"F") ("s"/"S") ("n"/"N") ) / ( ("f"/"F") ("u"/"U") ("l"/"L") ("l"/"L") ("y"/"Y") ("s"/"S") ("p"/"P") ("e"/"E") ("c"/"C") ("i"/"I") ("f"/"F") ("i"/"I") ("e"/"E") ("d"/"D") ("n"/"N") ("a"/"A") ("m"/"M") ("e"/"E") ) definition = ("d"/"D") ("e"/"E") ("f"/"F") [ ("i"/"I") ("n"/"N") ("i"/"I") ("t"/"T") ("i"/"I") ("o"/"O") ("n"/"N") ] dialectFilter = (dialectIdFilter / dialectAliasFilter) [ ws acceptabilitySet ] dialectIdFilter = dialectId ws booleanComparisonOperator ws (subExpressionConstraint / dialectIdSet) dialectId = ("d"/"D") ("i"/"I") ("a"/"A") ("l"/"L") ("e"/"E") ("c"/"C") ("t"/"T") ("i"/"I") ("d"/"D") dialectAliasFilter = dialect ws booleanComparisonOperator ws (dialectAlias / dialectAliasSet) dialect = ("d"/"D") ("i"/"I") ("a"/"A") ("l"/"L") ("e"/"E") ("c"/"C") ("t"/"T") dialectAlias = alpha *( dash / alpha / integerValue) dialectAliasSet = "(" ws dialectAlias [ws acceptabilitySet] *(mws dialectAlias [ws acceptabilitySet]) ws ")" dialectIdSet = "(" ws eclConceptReference [ws acceptabilitySet] *(mws eclConceptReference [ws acceptabilitySet] ) ws ")" acceptabilitySet = acceptabilityConceptReferenceSet / acceptabilityTokenSet acceptabilityConceptReferenceSet = "(" ws eclConceptReference *(mws eclConceptReference) ws ")" acceptabilityTokenSet = "(" ws acceptabilityToken *(mws acceptabilityToken) ws ")" acceptabilityToken = acceptable / preferred acceptable = ("a"/"A") ("c"/"C") ("c"/"C") ("e"/"E") ("p"/"P") ("t"/"T") [ ("a"/"A") ("b"/"B") ("l"/"L") ("e"/"E") ] preferred = ("p"/"P") ("r"/"R") ("e"/"E") ("f"/"F") ("e"/"E") ("r"/"R") [ ("r"/"R") ("e"/"E") ("d"/"D") ] conceptFilterConstraint = "{{" ws ("c" / "C") ws conceptFilter *(ws "," ws conceptFilter) ws "}}" conceptFilter = definitionStatusFilter / moduleFilter / effectiveTimeFilter / activeFilter definitionStatusFilter = definitionStatusIdFilter / definitionStatusTokenFilter definitionStatusIdFilter = definitionStatusIdKeyword ws booleanComparisonOperator ws (subExpressionConstraint / eclConceptReferenceSet) definitionStatusIdKeyword = ("d"/"D") ("e"/"E") ("f"/"F") ("i"/"I") ("n"/"N") ("i"/"I") ("t"/"T") ("i"/"I") ("o"/"O") ("n"/"N") ("s"/"S") ("t"/"T") ("a"/"A") ("t"/"T") ("u"/"U") ("s"/"S") ("i"/"I") ("d"/"D") definitionStatusTokenFilter = definitionStatusKeyword ws booleanComparisonOperator ws (definitionStatusToken / definitionStatusTokenSet) definitionStatusKeyword = ("d"/"D") ("e"/"E") ("f"/"F") ("i"/"I") ("n"/"N") ("i"/"I") ("t"/"T") ("i"/"I") ("o"/"O") ("n"/"N") ("s"/"S") ("t"/"T") ("a"/"A") ("t"/"T") ("u"/"U") ("s"/"S") definitionStatusToken = primitiveToken / definedToken definitionStatusTokenSet = "(" ws definitionStatusToken *(mws definitionStatusToken) ws ")" primitiveToken = ("p"/"P") ("r"/"R") ("i"/"I") ("m"/"M") ("i"/"I") ("t"/"T") ("i"/"I") ("v"/"V") ("e"/"E") definedToken = ("d"/"D") ("e"/"E") ("f"/"F") ("i"/"I") ("n"/"N") ("e"/"E") ("d"/"D") moduleFilter = moduleIdKeyword ws booleanComparisonOperator ws (subExpressionConstraint / eclConceptReferenceSet) moduleIdKeyword = ("m"/"M") ("o"/"O") ("d"/"D") ("u"/"U") ("l"/"L") ("e"/"E") ("i"/"I") ("d"/"D") effectiveTimeFilter = effectiveTimeKeyword ws timeComparisonOperator ws ( timeValue / timeValueSet ) effectiveTimeKeyword = ("e"/"E") ("f"/"F") ("f"/"F") ("e"/"E") ("c"/"C") ("t"/"T") ("i"/"I") ("v"/"V") ("e"/"E") ("t"/"T") ("i"/"I") ("m"/"M") ("e"/"E") timeValue = QM [ year month day ] QM timeValueSet = "(" ws timeValue *(mws timeValue) ws ")" year = digitNonZero digit digit digit month = "01" / "02" / "03" / "04" / "05" / "06" / "07" / "08" / "09" / "10" / "11" / "12" day = "01" / "02" / "03" / "04" / "05" / "06" / "07" / "08" / "09" / "10" / "11" / "12" / "13" / "14" / "15" / "16" / "17" / "18" / "19" / "20" / "21" / "22" / "23" / "24" / "25" / "26" / "27" / "28" / "29" / "30" / "31" activeFilter = activeKeyword ws booleanComparisonOperator ws activeValue activeKeyword = ("a"/"A") ("c"/"C") ("t"/"T") ("i"/"I") ("v"/"V") ("e"/"E") activeValue = activeTrueValue / activeFalseValue / wildCard activeTrueValue = "1" / "true" activeFalseValue = "0" / "false" memberFilterConstraint = "{{" ws ("m" / "M") ws memberFilter *(ws "," ws memberFilter) ws "}}" memberFilter = moduleFilter / effectiveTimeFilter / activeFilter / memberFieldFilter memberFieldFilter = refsetFieldName ws (expressionComparisonOperator ws subExpressionConstraint / numericComparisonOperator ws "#" numericValue / stringComparisonOperator ws (typedSearchTerm / typedSearchTermSet) / booleanComparisonOperator ws booleanValue / ws timeComparisonOperator ws (timeValue / timeValueSet) ) historySupplement = "{{" ws "+" ws historyKeyword [ historyProfileSuffix / ws historySubset ] ws "}}" historyKeyword = ("h"/"H") ("i"/"I") ("s"/"S") ("t"/"T") ("o"/"O") ("r"/"R") ("y"/"Y") historyProfileSuffix = historyMinimumSuffix / historyModerateSuffix / historyMaximumSuffix historyMinimumSuffix = ("-"/"_") ("m"/"M") ("i"/"I") ("n"/"N") historyModerateSuffix = ("-"/"_") ("m"/"M") ("o"/"O") ("d"/"D") historyMaximumSuffix = ("-"/"_") ("m"/"M") ("a"/"A") ("x"/"X") historySubset = "(" ws expressionConstraint ws ")" numericValue = ["-"/"+"] (decimalValue / integerValue) stringValue = 1*(anyNonEscapedChar / escapedChar) integerValue = digitNonZero *digit / zero decimalValue = integerValue "." 1*digit booleanValue = true / false true = ("t"/"T") ("r"/"R") ("u"/"U") ("e"/"E") false = ("f"/"F") ("a"/"A") ("l"/"L") ("s"/"S") ("e"/"E") nonNegativeIntegerValue = (digitNonZero *digit ) / zero sctId = digitNonZero 5*17( digit ) ws = *( SP / HTAB / CR / LF / comment ) ; optional white space mws = 1*( SP / HTAB / CR / LF / comment ) ; mandatory white space comment = "/*" *(nonStarChar / starWithNonFSlash) "*/" nonStarChar = SP / HTAB / CR / LF / %x21-29 / %x2B-7E /UTF8-2 / UTF8-3 / UTF8-4 starWithNonFSlash = %x2A nonFSlash nonFSlash = SP / HTAB / CR / LF / %x21-2E / %x30-7E /UTF8-2 / UTF8-3 / UTF8-4 SP = %x20 ; space HTAB = %x09 ; tab CR = %x0D ; carriage return LF = %x0A ; line feed QM = %x22 ; quotation mark BS = %x5C ; back slash star = %x2A ; asterisk digit = %x30-39 zero = %x30 digitNonZero = %x31-39 nonwsNonPipe = %x21-7B / %x7D-7E / UTF8-2 / UTF8-3 / UTF8-4 anyNonEscapedChar = SP / HTAB / CR / LF / %x20-21 / %x23-5B / %x5D-7E / UTF8-2 / UTF8-3 / UTF8-4 escapedChar = BS QM / BS BS escapedWildChar = BS QM / BS BS / BS star nonwsNonEscapedChar = %x21 / %x23-5B / %x5D-7E / UTF8-2 / UTF8-3 / UTF8-4 alpha = %x41-5A / %x61-7A dash = %x2D UTF8-2 = %xC2-DF UTF8-tail UTF8-3 = %xE0 %xA0-BF UTF8-tail / %xE1-EC 2( UTF8-tail ) / %xED %x80-9F UTF8-tail / %xEE-EF 2( UTF8-tail ) UTF8-4 = %xF0 %x90-BF 2( UTF8-tail ) / %xF1-F3 3( UTF8-tail ) / %xF4 %x80-8F 2( UTF8-tail ) UTF8-tail = %x80-BF ``` {% endcode %} --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://docs.snomed.org/snomed-ct-specifications/snomed-ct-expression-constraint-language/design/5-syntax-specification/long-syntax.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.