The Orientation menu allows you to select the page orientation of your document. You may choose Portrait, Landscape, Upside-down, or Seascape as your orientation.
Portrait is the natural orientation for a given media; in most cases, the short sides will be at the top and bottom.
Landscape is a clockwise rotation of 90 degrees. Some PostScript producers get things backwards and rotate counter-clockwise so you might have to use the Seascape orientation instead.
Upside-down is a rotation of 180 degrees. Note that this is not a reflection so Upside-down may be misleading.
Seascape is a clockwise rotation of 270 degrees. Some PostScript documents that claim to be landscape have actually been rotated by 90 degrees counter-clockwise so you might have to use this orientation to get a landscape document to appear right-side-up.
If you explicitly force an orientation, mgv will preserve it if you reopen the current document.