EBNF

A continuación mostramos la gramática EBNF:

Document         ::= Line*

Line             ::= EmptyLine | CommentLine | NodeLine | BlockContentLine
EmptyLine        ::= Newline

CommentLine      ::= IndentOpt? "#" TEXT? Newline

NodeLine         ::= IndentPrefix NodeHeader (Separator InlineValue)? Newline

NodeHeader       ::= NodeName NamespaceOpt (BlockOp |)
BlockOp          ::= ">>"
Separator        ::= ":"
InlineValue      ::= TEXT

BlockStart       ::= IndentPrefix NodeName NamespaceOpt BlockOp Newline
BlockContentLine ::= IndentGreaterThan(NodeIndent) TEXT? Newline

NamespaceOpt     ::= "(" "@" Identifier ("." Identifier)* ")"

NodeName         ::= Identifier

IndentOpt        ::= (TAB | SPACES4)*
IndentPrefix     ::= IndentOpt
IndentGreaterThan(nodeIndent) ::= (line indentation) > nodeIndent

SPACES4          ::= "    "
TAB              ::= "\t"
Newline          ::= "\n" | "\r\n"
Identifier       ::= IdentifierChar ( IdentifierChar )*
IdentifierChar   ::= Letter | Digit | "_" | "-" | " " | "."
Letter           ::= ? any Unicode letter ?
Digit            ::= "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
TEXT             ::= ? any printable character except newline ?