Push saves the current orientation of all open models on an image stack. (For those unfamiliar with the concept of a "stack," think of a pile of pictures which is created by "pushing" pictures one at a time onto the top of the pile and in which pictures are retrieved one at a time by taking the top picture off the pile.) Pop retrieves the last "pushed" orientation. Any number of model orientations may be saved on the stack, memory allowing, and retrieved on a last-in first-out basis.
See also: align, reset, savepos, window