This article is from the Backgammon FAQ, by Mark Damish damish@ll.mit.edu with numerous contributions by others.
From the FIBS help screens:
If you are playing an n-point match and your opponent is ahead
of you and he gets to n-1 points you are not allowed to use
the doubling cube in the next game to come
EXAMPLE: 5 point match score game # You opponent 1 0 3 2 0 4 3 1 4 (you were not allowed to double in this game) 4 3 4 (you were allowed to double again) ... ... ...
 
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