The autoflip mechanism can be turned on/off at startup using the command switch "-autoflip true|false" or the SAOTNG_AUTOFLIP environment variable. While SAOtng is running, autoflipping can be toggled from the Zoom menu. When turned off, the menu option is "Enable Auto-Flip". When turned on, the menu option is "Disable Auto-Flip". Auto-flip also can be set using the "zoom" XPA access point.
Auto-flip requires that WCS information be available in the newly loaded image header. If the CD1_1 or CDELT1 parameter (in that order) is positive, then the image is flipped in x. If the CD2_2 or CDELT2 parameter (in that order) is positive, then the image is flipped in y. If none of these parameters exist, then no auto-flipping is performed. Note that auto-flipping also is not performed if the current frame already has been flipped by the user.