anchor.diff:      token TOKDEPENDENCIES: "dependencies"
       token TOKDERIVING: "deriving"
       token TOKDETERMINES: "determines"
  -    token TOKDOC: "doc"
       token TOKELSE: "else"
       token TOKENABLE: "enable"
       token TOKEND: "end"
  
positive.code:     token TOKPACKAGE: "package"
      token TOKPAR: "par"
      token TOKPARAMETER: "parameter"
      token TOKPREFIX: "prefix"
      token TOKPROVISOS: "provisos"
      token TOKREADY: "ready"
      token TOKREAL: "Real"
      token TOKRESET_BY: "reset_by"
      token TOKRESULT: "result"
      token TOKRETURN: "return"
  
negative.code:          TOKLET
              ( VAR | LBRACE VAR (COMMA VAR)* RBRACE)
              assign_opvalue SEMICOLON
          | typevar_item declared_item ( COMMA declared_item )* SEMICOLON
          | expr<<[]>>
              [   ( declared_item ( COMMA declared_item )*
                  | assign_opvalue
  