anchor.diff:  frequency   : 'FREQUENCY' estimate (',' estimate)*;
   estimate    : statementNumber '(' ufixedConst (',' ufixedConst)* ')';
   
  +
   // http://www.fortran.com/FortranForTheIBM704.pdf#12
   variable   : VAR_ID | FUNC_CANDIDATE;
   // http://www.fortran.com/FortranForTheIBM704.pdf#13
  
positive.code:                         on=statementNumber ',' off=statementNumber;
  ifDivideCheck         : 'IF' 'DIVIDE' 'CHECK'
                          on=statementNumber ',' off=statementNumber;
  
  // http://www.fortran.com/FortranForTheIBM704.pdf#22
  doLoop       : 'DO' range=statementNumber index=variable '=' first=loopBoundary ','
  
negative.code: // http://www.fortran.com/FortranForTheIBM704.pdf#18
  arithmeticFormula : (VAR_ID | FUNC_CANDIDATE | subscript) '=' expression;
  
  
  // http://www.fortran.com/FortranForTheIBM704.pdf#19
  uncondGoto   : 'GO' 'TO' statementNumber;
  assignedGoto : 'GO' 'TO' variable ',' '(' statementNumber (',' statementNumber)* ')';
  assign       : 'ASSIGN' statementNumber 'TO' variable;
  computedGoto : 'GO' 'TO' '(' statementNumber (',' statementNumber)* ')' ',' variable;
  
  
  // http://www.fortran.com/FortranForTheIBM704.pdf#20
  ifStatement           : 'IF' '(' condition=expression ')' lessThan=statementNumber ','
  