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/* [dtd.abs]                   Abstract Grammar                             */
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LANGUAGE dtd

TOKENS

  PERef, Nmtoken, XMLDecl, PI, Keyset, Name, Literal, DTDStart, IgnSect

TYPES

  dtd           = Start_Root(Root);
                  Start_Embed(Embed)

  Root          = text(Extern);
                  tdoc(DTDStart, Embed)

  Embed         = dfn(XName, ExtID, Decl*)

  Extern        = dfn(XDecl, Decl*)

  XDecl         = nul;
                  dfn(XMLDecl)

  ExtID         = pref(PERef);
                  nul;
                  pub(XLiteral, XLiteral);
                  sys(XLiteral)

  XLiteral      = pref(PERef);
                  lit(Literal);
                  nul

  Decl          = pref(PERef);
                  attr(XName, Attribute*);
                  ent(Entity);
                  pi(PI);
                  note(XName, ExtID);
                  elm(XName, Content);
                  cond(Cond)

  Cond          = cinc(Extern);
                  cign(IgnSect);
                  ccnd(PERef, Extern)

  Attribute     = nam(XName);
                  dft(ADefault);
                  typ(AType)

  AType         = refs;
                  nmts;
                  str;
                  ents;
                  etyp(XName*);
                  ref;
                  nmt;
                  ntyp;
                  id;
                  ent

  ADefault      = fix(Fixed, Literal);
                  imp;
                  req

  Fixed         = nul;
                  fix

  Entity        = pent(XName, EntityVal);
                  gent(XName, EntityVal)

  EntityVal     = ient(XLiteral);
                  eent(ExtID, NData)

  NData         = nul;
                  dfn(XName, XName)

  Content       = alt(Content, Content);
                  none;
                  mix(XName*);
                  any;
                  seq(Content, Content);
                  nam(XName, ROpr);
                  rexp(Content, ROpr);
                  pref(PERef)

  ROpr          = nul;
                  plus;
                  star;
                  qry

  XName         = elm;
                  req;
                  key(Keyset);
                  alst;
                  pref(PERef);
                  fix;
                  inc;
                  ndat;
                  pub;
                  nmtk(Nmtoken);
                  none;
                  pdat;
                  ide(Name);
                  any;
                  impl;
                  ktyp(AType);
                  sys