In fact, I've just found another reasonable classification.
That's the current one (with slightly clearer text, I think) :
Wrong double (below DP)
Wrong double (above TG)
Missed double (above DP) (around DP in GNUbg)
Missed double (around CP) (around CP in GNUbg)
Missed double (below TG) (arounf TG in GNUbg)
That's the last one I came up with :
Wrong double (below DP)
Wrong double (above TG)
Missed double (below CP) (and above DP, that's implicit)
Missed double (above CP) (and below TG, that's implicit)
In fact, when you miss below CP, it was a Double/Take, when you miss above
CP it was a Double/Pass. This classification has 2 advantages :
1) 2 Missed catagories instead of 3 : should be easier to handle
exotic cases (like TG<DP), since there's only one separator
(CP) and CP is always above DP (right ?).
2) It tells you what the opponent should have done (take/pass),
which is probably the only meaningful information.
Many beginners (and some intermediate to advanced) players
will notice that they miss much more double/take than double/pass.
So my final suggestion for double classification (at least for today) is :
Wrong double (below DP)
Wrong double (above TG)
Missed double (below CP) or Missed double/take (below CP)
Missed double (above CP) or Missed double/pass (above CP)