Orientation of the Characters

Sometimes an Indus sign will be the obvious equivalent of a Chinese sign, but the Chinese sign will have been rotated 90 degrees to the right.

My understanding is that Middle Egyptian signs changed orientation, when the direction of the script changed. It may be that at some point, someone changed the orientation of a character to match the change in orientation of a script, but when the orientation of the script changed again, the orientation of the character didn't.