{ Invisible XML specification grammar, 2026-02-03 }
{ Published in https://invisiblexml.org/current/ }
{ Commit hash ca938ecd6297 }

         ixml: s, (prolog, RS)?, rule++RS, s.
           -s: (whitespace; comment)*. {Optional spacing}
          -RS: (whitespace; comment)+. {Required spacing}
  -whitespace: -[Zs]; tab; lf; cr.
         -tab: -#9.
          -lf: -#a.
          -cr: -#d.
      comment: -"{", (cchar; comment)*, -"}".
       -cchar: ~["{}"].
       prolog: version.
      version: -"ixml", RS, -"version", RS, string, s, -'.' .
         rule: naming, -["=:"], s, -alts, -".".
      -naming: (mark, s)?, name, s, (-">", s, alias, s)?.
        @name: namestart, namefollower*.
   -namestart: ["_"; L].
-namefollower: namestart; ["-.·‿⁀"; Nd; Mn].
       @alias: name.
         alts: alt++(-[";|"], s).
          alt: term**(-",", s).
        -term: factor;
               option;
               repeat0;
               repeat1.
      -factor: terminal;
               nonterminal;
               insertion;
               -"(", s, alts, -")", s.
      repeat0: factor, (-"*", s; -"**", s, sep).
      repeat1: factor, (-"+", s; -"++", s, sep).
       option: factor, -"?", s.
        @mark: ["@^-"].
          sep: factor.
  nonterminal: naming.
    -terminal: literal; 
               charset.
      literal: quoted;
               encoded.
      -quoted: (tmark, s)?, string, s.

       @tmark: ["^-"].
      @string: -'"', dchar+, -'"';
               -"'", schar+, -"'".
        dchar: ~['"'; Cc];
               '"', -'"'. {all characters except controls; quotes must be doubled}
        schar: ~["'"; Cc];
               "'", -"'". {all characters except controls; quotes must be doubled}
     -encoded: (tmark, s)?, -"#", hex, s.
         @hex: ["0"-"9"; "a"-"f"; "A"-"F"]+.
     -charset: inclusion; 
               exclusion.
    inclusion: (tmark, s)?,          set.
    exclusion: (tmark, s)?, -"~", s, set.
         -set: -"[", s,  (member, s)**(-[";|"], s), -"]", s.
       member: string;
               -"#", hex;
               range;
               class.
       -range: from, s, -"-", s, to.
        @from: character.
          @to: character.
   -character: -'"', dchar, -'"';
               -"'", schar, -"'";
               "#", hex.
       -class: code.
        @code: capital, letter?.
     -capital: ["A"-"Z"].
      -letter: ["A"-"Z"; "a"-"z"].
    insertion: -"+", s, (string; -"#", hex), s.