Thanks! Would this effect how the current HA/DE axis simulation work?

Thanks! Would this effect how the current HA/DE axis simulation work?

No, the ALTAZ track simulation works independently and is currently triggered by view switch (star globe view -> EQ / horizontal view -> ALTAZ)
BTW: I'm currently working on ALTAZ sim FOV simulation, which is more complicated than I thought. This will be implemented in ccd-simulator (INDI) and skymap (KStars/EKOS part of derotation option).

@escribana Thank you, does this PR alter the current behavior of the drivers if the rotation was zero?

I don't know which rotation you mean: We have several of them! There is a "camera rotation" (A) in ccd_simulator.cpp measured as full circle from origin north CCW. Then there is the absolute rotator angle (B) measured the same way as the mentioned "camera rotation" of the simulator. All other rotation angles (C) are measured with the PA-scheme (real camera rotation and real camera offset ). And finally there is the CROTA1/2-entry in the fits header which is calculated with -PA+180°.

Regarding this PR I can summarize the two most important points:

1. The PR doesn't change the meaning of CCD_ROTATION in indiccd.cpp. It's only renamed to "Orientation" (following the notation of astrometry.net ) to prevent a confusion with all other "rotations". "Orientation" appears in the WCS tab of INDI Control after a plate solving.
2. the "CCD Rotation" (SimulatorSettingsNP[SIM_ROTATION] in ccd_simulator.cpp (formerly not used as a variable and hard coded to 270°) is now used as "camera rotation"/rotatorangle of type (A). So this modification does not affect any rotation in any driver.