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The following ABNF definition specifies the Long Syntax the 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 repository.
expressionConstraint
= ws ( refinedExpressionConstraint / compoundExpressionConstraint / dottedExpressionConstraint / subExpressionConstraint ) wsrefinedExpressionConstraint=simpleExpressionConstraintsubExpressionConstraint ws ":" ws eclRefinementcompoundExpressionConstraint= conjunctionExpressionConstraint / disjunctionExpressionConstraint / exclusionExpressionConstraintconjunctionExpressionConstraint= subExpressionConstraint 1*(ws conjunction ws subExpressionConstraint)disjunctionExpressionConstraint= subExpressionConstraint 1*(ws disjunction ws subExpressionConstraint)exclusionExpressionConstraint= subExpressionConstraint ws exclusion ws subExpressionConstraintdottedExpressionConstraint= subExpressionConstraint 1*(wsdot ws [attributeOperator ws] eclAttributeName)subExpressionConstraint = [constraintOperator ws] [memberOf ws] (eclFocusConcept / "(" ws expressionConstraint ws ")")
simpleExpressionConstraint = [constraintOperator ws] [memberOf ws] eclFocusConcept
eclFocusConcept = conceptReference / wildCard
dot = "."
memberOf = "^" /dottedExpressionAttribute) dottedExpressionAttribute = dot ws eclAttributeName subExpressionConstraint= [constraintOperator ws] ( ( [memberOf ws] (eclFocusConcept / "(" ws expressionConstraint ws ")") *(ws memberFilterConstraint)) / (eclFocusConcept / "(" ws expressionConstraint ws ")") ) *(ws (descriptionFilterConstraint / conceptFilterConstraint)) [ws historySupplement] eclFocusConcept = eclConceptReference / wildCard / altIdentifier dot = "." memberOf = ( "^" / ("m"/"M") ("e"/"E") ("m"/"M") ("b"/"B") ("e"/"E") ("r"/"R") ("o"/"O") ("f"/"F")conceptReference = conceptId [ws "|" ws term ws "|"]
conceptId = sctId
term = 1*nonwsNonPipe *( 1*SP 1*nonwsNonPipe )
wildCard = "*" / ( ("a"/"A") ("n"/"N") ("y"/"Y") )
constraintOperator = childOf / descendantOrSelfOf / descendantOf / parentOf / ancestorOrSelfOf / ancestorOf
descendantOf = "<" / ( () ) [ ws "[" ws (refsetFieldNameSet / wildCard) ws "]" ] 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 = "<!" / (("c"/"C") ("h"/"H") ("i"/"I") ("l"/"L") ("d"/"D") ("o"/"O") ("f"/"F") mws ) childOrSelfOf = "<<!" / (("c"/"C") ("h"/"H") ("i"/"I") ("l"/"L") ("d"/"D") ("o"/"O") ("r"/"R") ("s"/"S") ("e"/"E") ("l"/"L") ("f"/"F") ("o"/"O") ("f"/"F") mws ) ancestorOf = ">" / ( ("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 (typedSearchTerm / typedSearchTermSet) / 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 ")" 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") ("si"/"SI") ("cn"/"CN") ("ei"/"EI") ("nt"/"NT") ("di"/"DI") ("ao"/"AO") ("n"/"N") ("ts"/"TS") ("ot"/"OT") ("fa"/"FA")mws )descendantOrSelfOf = "<<" / ( ("d("t"/"DT") ("eu"/"EU") ("s"/"S")("c"/"C") ("e"/"E") ("n"/"N") ("d"/"D") ("a"/"A") ("n"/"N")definitionStatusToken = primitiveToken / definedToken definitionStatusTokenSet = "(" ws definitionStatusToken *(mws definitionStatusToken) ws ")" primitiveToken = ("p"/"P") ("r"/"R") ("i"/"I") ("m"/"M") ("i"/"I") ("t"/"T") ("oi"/"OI") ("rv"/"RV")("s"/"S")("e"/"E")("l"/"L")definedToken = ("fd"/"FD") ("oe"/"OE") ("f"/"F")mws )childOf = "<!" / (("c("i"/"CI") ("hn"/"HN") ("ie"/"IE") ("ld"/"L") ("dD") moduleFilter = moduleIdKeyword ws booleanComparisonOperator ws (subExpressionConstraint / eclConceptReferenceSet) moduleIdKeyword = ("m"/"DM") ("o"/"O") ("fd"/"FD")mws )ancestorOf = ">" / ( ("a("u"/"U") ("l"/"AL") ("ne"/"NE") ("ci"/"CI") ("ed"/"ED")("s"/"S") ("t"/"T") ("o"/"O") ("r"/"R") ("o"/"O") ("f"/"F") mws )ancestorOrSelfOf = ">>" / ( ("a"/"A") ("n"/"N") ("c"/"C")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") ("st"/"ST") ("ti"/"TI") ("om"/"OM") ("re"/"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 )
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] [attributeOperator ws] eclAttributeName ws (expressionComparisonOperator ws subExpressionConstraint / numericComparisonOperator ws "#" numericValue / stringComparisonOperator ws QM stringValue QM)
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 = (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 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") ("ey"/"E") ("v"Y") historyProfileSuffix = historyMinimumSuffix / historyModerateSuffix / historyMaximumSuffix historyMinimumSuffix = ("-"/"V_") ("em"/"EM") ("ri"/"RI") ("sn"/"SN") historyModerateSuffix = ("e-"/"E_") ("om"/"OM")("f"/"F")) / "R"attributeOperator = descendantOrSelfOf / descendantOf
eclAttributeName = conceptReference / wildCard
expressionComparisonOperator = "=("o"/"!=O"/) ("nd"/"ND") historyMaximumSuffix = ("o-"/"O_") ("tm"/"TM")ws("=a"/"<>"numericComparisonOperator = "=A") ("x"/"!=" / ("n"X") historySubset = "(" ws expressionConstraint ws ")" numericValue = ["-"/"N") ("o"/"O")+"] (decimalValue / integerValue) stringValue = 1*(anyNonEscapedChar / escapedChar) integerValue = digitNonZero *digit / zero decimalValue = integerValue "." 1*digit booleanValue = true / false true = ("t"/"T")ws("=r"/"<>R"/ "<=) ("u"/"<U"/ ">=) ("e"/">"stringComparisonOperator = "=" / "!=" / ("nE") false = ("f"/"NF") ("oa"/"OA") ("tl"/"TL")ws "=" / "<>"numericValue = ["-("s"/"+S"] (decimalValue / integerValue)stringValue = 1*(anyNonEscapedChar / escapedChar)
integerValue = digitNonZero *digit / zero
decimalValue = integerValue "." 1*digit
nonNegativeIntegerValue = (digitNonZero *digit ) / zero
sctId = digitNonZero) ("e"/"E") nonNegativeIntegerValue = (digitNonZero *digit ) / zero sctId = digitNonZero 5*17( digit )ws = *( SP / HTAB / CR / LF / comment ) ; optional white spacemws = 1*( SP / HTAB / CR / LF / comment ) ; mandatory white spacecomment = "/*" *(nonStarChar / starWithNonFSlash) "*/"nonStarChar = SP / HTAB / CR / LF / %x21-29 / %x2B-7E /UTF8-2 / UTF8-3 / UTF8-4starWithNonFSlash = %x2A nonFSlashnonFSlash = SP / HTAB / CR / LF / %x21-2E / %x30-7E /UTF8-2 / UTF8-3 / UTF8-4SP = %x20 ; spaceHTAB = %x09 ; tabCR = %x0D ; carriage returnLF = %x0A ; line feedQM = %x22 ; quotation markBS = %x5C ; backslashdigit =slash star = %x2A ; asterisk digit = %x30-39zero = %x30digitNonZero = %x31-39nonwsNonPipe = %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 / UTF8-4anyNonEscapedChar = SP / HTAB / CR / LF / %x20-21 / %x23-5B / %x5D-7E / UTF8-2 / UTF8-3 / UTF8-4
escapedChar = BS QM / BS BS
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 =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