anchor.diff:  
   //- ==== Energy section (4.2) ====
   
  -| 
  -|   energy  #{energy.form}
  -| 
  +//- FIXME error with isothermal
  +//- | 
  +//- |   energy  #{energy.form}
  +//- | 
   
   //- ==== Hydrostat section (4.3) ====
   
  
positive.code: | 
  
  //- ==== Output section (3.6) ====
  
  | 
  |   dump     #{output.dump}
  |   plti     #{output.plti}
  |   prtlev   #{output.prtlev}
  |   prti     #{output.prti}
  |   thti     #{output.thti}
  |   ttyi     #{output.ttyi}
  |   pltype   #{output.pltype}
  
negative.code: |      turbnu       #{initial.turbnu}
  |      temperature  #{initial.temperature}
  |      enthalpy     #{initial.enthalpy}
  |   end
  | 
  
  