This answer to a related question suggests that the order in which rotations around three principal axes are applied (in order to estimate the conversion of an attitude to a set of roll, pitch and yaw figures) is important.
This leads to another question: How exactly were CSM maneuvers for the purpose of changing its attitude performed?
Were there three separate consecutive sets of firings of the RCS thrusters (i.e. one firing to rotate around one axis, then firing to come to stop, then another firing around second axis, come to stop, then third firing around third axis, come to stop), or was there a multiple simultaneous firing of various RCS thrusters at once (i.e. to get to the the new required attitude in one go, so to speak)?
If it is the former, was there a rule for a specific order to be followed, for example, first Roll, then Pitch, after that Yaw, or maybe first Pitch, then Yaw after that Roll?
Let's consider a particular example from Apollo 11 Flight Journal. Capcom Bruce McCandless at 025:49:20 into the flight gives PAD for Midcourse Correction burn number 2. The Journal editors give the following interpretation for the spacecraft attitude:
Spacecraft attitude: Roll, 277°; Pitch, 355°; Yaw, 15°. This is with respect to the attitude of the guidance platform, itself aligned to the PTC REFSMMAT.
If I understand the quote correctly, then regardless of current CSM attitude, at the end of the maneuver, the spacecraft will have to be positioned at Roll 277°; Pitch, 355° and Yaw, 15° with respect to the corresponding axes of the current alignment of the guidance platform.
I assume the astronauts just plug in the numbers in DSKY, and computer does the calculation to get them from whatever their current attitude is to the required one.