Setaspect
setaspect <viewingrange> <yxaspect> is used to set the field of view in both dimensions in the original BUILD renderer. <viewingrange> is the horizontal FOV and is set to 65536 by default. <yxaspect> is (presumably?) the Y to X ratio multiplied by 65536. In the editor, its default value is (65536*ydim*8)/(xdim*5). Note that <yxaspect> also affects rotatesprite.