  :
  -      
   .      .   .     4 ,      .  ,       "t<xxx>".

t<xxx> 
    <xxx> /.     40.

<><><><> 
  ,      1/4    "c12 ".
<>:  "a"-"g",  "C","D","F","G","A",   "r".
<>: "0"-"3"  "4"   "f".
<>: "0"-"5" (, , , , ).
<>: " "   , "."   . 
