From Max Friis page http://xfriis.dk/maxfriis/bg/double.html Cash-point(CP) is: your opponent's take-point now seen from your side of the board (your cash-point which equals 100% minus your opponent's take-point). GNU Backgammon uses the term missed double below cash-point, which means that the player should have doubled, and had he done so, his opponent should take. . Missed double above CP in a similar way means that the correct cube-action was double pass.
If you are the leader in the match, the relevant take- and double-points will often look something like this (where TP*=CP):
The double line
The double windows (intervals) are:
[DP;CP] = Your double window! This window does not contain any information about redoubles but only the distance to the point where you do not want to play for the double amount of points.
[TP;DP] = 100% minus your opponent's double window now.
[reTP;reDP] = 100% minus your opponent's double window after he has taken.