You can change the range of allowed priorities by setting the variables org-highest-priority, org-lowest-priority, and org-default-priority. For an individual buffer, you may set these values (highest, lowest, default) like this (please make sure that the highest priority is earlier in the alphabet than the lowest priority):
#+PRIORITIES: A C B
Pay attention to this:
(...) please make sure that the highest priority is earlier in the alphabet than the lowest priority
Is not possible to define, for example, the following order: A, C, B and D?
If I use the org-mode API The priority A always has a smaller number than B, and B than C and so on.
I use this matrix:
Where A is urgent and important. B is important but not urgent. And C is urgent but not important. So, C should be "higher priority" than B because it should be done first.
Is that possible to invert the order of priority letters? A, C, B and D? Or not?