Extended Backus–Naur Form (EBNF) is a syntax for specifying context free grammars. The following EBNF specifies the syntax for XML 1.1.

 

[1]   document          ::= prolog element Misc* - Char* RestrictedChar Char*
[2]   Char              ::= [#x1-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF] /* any Unicode character, excluding the surrogate blocks, FFFE, and FFFF. */
[2a]  RestrictedChar    ::= [#x1-#x8] | [#xB-#xC] | [#xE-#x1F] | [#x7F-#x84] | [#x86-#x9F]
[3]   S                 ::= (#x20 | #x9 | #xD | #xA)+
[4]   NameStartChar     ::= ":" | [A-Z] | "_" | [a-z] | [#xC0-#xD6] | [#xD8-#xF6] | [#xF8-#x2FF] | [#x370-#x37D] | [#x37F-#x1FFF] | [#x200C-#x200D] | [#x2070-#x218F] | [#x2C00-#x2FEF] | [#x3001-#xD7FF] | [#xF900-#xFDCF] | [#xFDF0-#xFFFD] | [#x10000-#xEFFFF]
[4a]  NameChar          ::= NameStartChar | "-" | "." | [0-9] | #xB7 | [#x0300-#x036F] | [#x203F-#x2040]
[5]   Name              ::= NameStartChar (NameChar)*
[6]   Names             ::= Name (#x20 Name)*
[7]   Nmtoken           ::= (NameChar)+
[8]   Nmtokens          ::= Nmtoken (#x20 Nmtoken)*
[9]   EntityValue       ::= '"' ([^%&"] | PEReference | Reference)* '"' | "'" ([^%&'] | PEReference | Reference)* "'"
[10]  AttValue          ::= '"' ([^<&"] | Reference)* '"' | "'" ([^<&'] | Reference)* "'"
[11]  SystemLiteral     ::= ('"' [^"]* '"') | ("'" [^']* "'")
[12]  PubidLiteral      ::= '"' PubidChar* '"' | "'" (PubidChar - "'")* "'"
[13]  PubidChar         ::= #x20 | #xD | #xA | [a-zA-Z0-9] | [-'()+,./:=?;!*#@$_%]
[14]  CharData          ::= [^<&]* - ([^<&]* ']]>' [^<&]*)
[15]  Comment           ::= '<!--' ((Char - '-') | ('-' (Char - '-')))* '-->'
[16]  PI                ::= '<?' PITarget (S (Char* - (Char* '?>' Char*)))? '?>'
[17]  PITarget          ::= Name - (('X' | 'x') ('M' | 'm') ('L' | 'l'))
[18]  CDSect            ::= CDStart CData CDEnd
[19]  CDStart           ::= '<![CDATA['
[20]  CData             ::= (Char* - (Char* ']]>' Char*))
[21]  CDEnd             ::= ']]>'
[22]  prolog            ::= XMLDecl Misc* (doctypedecl Misc*)?
[23]  XMLDecl           ::= '<?xml' VersionInfo EncodingDecl? SDDecl? S?'?>'
[24]  VersionInfo       ::= S 'version' Eq ("'" VersionNum "'" | '"' VersionNum '"')
[25]  Eq                ::= S? '=' S?
[26]  VersionNum        ::= '1.1'
[27]  Misc              ::= Comment | PI | S
[28]  doctypedecl       ::= '<!DOCTYPE' S Name (S ExternalID)? S? ('[' intSubset ']' S?)? '>'
[28a] DeclSep           ::= PEReference | S
[28b] intSubset         ::= (markupdecl | DeclSep)*
[29]  markupdecl        ::= elementdecl | AttlistDecl | EntityDecl | NotationDecl | PI | Comment
[30]  extSubset         ::= TextDecl? extSubsetDecl
[31]  extSubsetDecl     ::= ( markupdecl | conditionalSect | DeclSep)*
[32]  SDDecl            ::= #x20+ 'standalone' Eq (("'" ('yes' | 'no') "'") | ('"' ('yes' | 'no') '"'))
(Productions 33 through 38 have been removed.)
[39]  element           ::= EmptyElemTag
[40]  STag              ::= '<' Name (S Attribute)* S? '>'
[41]  Attribute         ::= Name Eq AttValue
[42]  ETag              ::= '</' Name S? '>'
[43]  content           ::= CharData? ((element | Reference | CDSect | PI | Comment) CharData?)*
[44]  EmptyElemTag      ::= '<' Name (S Attribute)* S? '/>'
[45]  elementdecl       ::= '<!ELEMENT' S Name S contentspec S? '>'
[46]  contentspec       ::= 'EMPTY' | 'ANY' | Mixed | children
[47]  children          ::= (choice | seq) ('?' | '*' | '+')?
[48]  cp                ::= (Name | choice | seq) ('?' | '*' | '+')?
[49]  choice            ::= '(' S? cp ( S? '|' S? cp )+ S? ')'
[50]  seq               ::= '(' S? cp ( S? ',' S? cp )* S? ')'
[51]  Mixed             ::= '(' S? '#PCDATA' (S? '|' S? Name)* S? ')*' | '(' S? '#PCDATA' S? ')'
[52]  AttlistDecl       ::= '<!ATTLIST' S Name AttDef* S? '>'
[53]  AttDef            ::= S Name S AttType S DefaultDecl
[54]  AttType           ::= StringType | TokenizedType | EnumeratedType
[55]  StringType        ::= 'CDATA'
[56]  TokenizedType     ::= 'ID' | 'IDREF' | 'IDREFS' | 'ENTITY' | 'ENTITIES' | 'NMTOKEN' | 'NMTOKENS'
[57]  EnumeratedType    ::= NotationType | Enumeration
[58]  NotationType      ::= 'NOTATION' S '(' S? Name (S? '|' S? Name)* S? ')'
[59]  Enumeration       ::= '(' S? Nmtoken (S? '|' S? Nmtoken)* S? ')'
[60]  DefaultDecl       ::= '#REQUIRED' | '#IMPLIED' | (('#FIXED' S)? AttValue)
[61]  conditionalSect   ::= includeSect | ignoreSect
[62]  includeSect       ::= '<![' S? 'INCLUDE' S? '[' extSubsetDecl ']]>'
[63]  ignoreSect        ::= '<![' S? 'IGNORE' S? '[' ignoreSectContents* ']]>'
[64]  ignoreSectContents::= Ignore ('<![' ignoreSectContents ']]>' Ignore)*
[65]  Ignore            ::= Char* - (Char* ('<![' | ']]>') Char*)
[66]  CharRef           ::= '&#' [0-9]+ ';' | '&#x' [0-9a-fA-F]+ ';'
[67]  Reference         ::= EntityRef | CharRef
[68]  EntityRef         ::= '&' Name ';'
[69]  PEReference       ::= '%' Name ';'
[70]  EntityDecl        ::= GEDecl | PEDecl
[71]  GEDecl            ::= '<!ENTITY' S Name S EntityDef S? '>'
[72]  PEDecl            ::= '<!ENTITY' S '%' S Name S PEDef S? '>'
[73]  EntityDef         ::= EntityValue| (ExternalID NDataDecl?)
[74]  PEDef             ::= EntityValue | ExternalID
[75]  ExternalID        ::= 'SYSTEM' S SystemLiteral | 'PUBLIC' S PubidLiteral S SystemLiteral
[76]  NDataDecl         ::= S 'NDATA' S Name
[77]  TextDecl          ::= '<?xml' VersionInfo? EncodingDecl S? '?>'
[78]  extParsedEnt      ::= TextDecl? content - Char* RestrictedChar Char*
[80]  EncodingDecl      ::= S 'encoding' Eq ('"' EncName '"' | "'" EncName "'" )
[81]  EncName           ::= [A-Za-z] ([A-Za-z0-9._] | '-')*
[82]  NotationDecl      ::= '<!NOTATION' S Name S (ExternalID | PublicID) S? '>'
[83]  PublicID          ::= 'PUBLIC' S PubidLiteral