+.PP
+The following three options are mutually exclusive. They determine
+which Klein bottle is displayed.
+.TP 8
+.B \-klein-bottle random
+Display a random Klein bottle (default).
+.TP 8
+.B \-klein-bottle figure-8 \fP(Shortcut: \fB\-figure-8\fP)
+Display the figure-8 Klein bottle.
+.TP 8
+.B \-klein-bottle lawson \fP(Shortcut: \fB\-lawson\fP)
+Display the Lawson Klein bottle.
+.PP
+The following four options are mutually exclusive. They determine
+how the Klein bottle is displayed.
+.TP 8
+.B \-mode random
+Display the Klein bottle in a random display mode (default).
+.TP 8
+.B \-mode wireframe \fP(Shortcut: \fB\-wireframe\fP)
+Display the Klein bottle as a wireframe mesh.
+.TP 8
+.B \-mode surface \fP(Shortcut: \fB\-surface\fP)
+Display the Klein bottle as a solid surface.
+.TP 8
+.B \-mode transparent \fP(Shortcut: \fB\-transparent\fP)
+Display the Klein bottle as a transparent surface.
+.PP
+The following three options are mutually exclusive. They determine the
+appearance of the Klein bottle.
+.TP 8
+.B \-appearance random
+Display the Klein bottle with a random appearance (default).
+.TP 8
+.B \-appearance solid \fP(Shortcut: \fB\-solid\fP)
+Display the Klein bottle as a solid object.
+.TP 8
+.B \-appearance bands \fP(Shortcut: \fB\-bands\fP)
+Display the Klein bottle as see-through bands.
+.PP
+The following four options are mutually exclusive. They determine
+how to color the Klein bottle.
+.TP 8
+.B \-colors random
+Display the Klein bottle with a random color scheme (default).
+.TP 8
+.B \-colors twosided \fP(Shortcut: \fB\-twosided\fP)
+Display the Klein bottle with two colors: red on one "side" and green
+on the "other side".
+.TP 8
+.B \-colors rainbow \fP(Shortcut: \fB\-rainbow\fP)
+Display the Klein bottle with fully saturated rainbow colors. If the
+Klein bottle is displayed as see-through bands, each band will be
+displayed with a different color.
+.TP 8
+.B \-colors depth \fP(Shortcut: \fB\-depth\fP)
+Display the Klein bottle with colors chosen depending on the 4d
+"depth" of the points.
+.PP
+The following four options are mutually exclusive. They determine
+how to view the Klein bottle.
+.TP 8
+.B \-view-mode random
+View the Klein bottle in a random view mode (default).
+.TP 8
+.B \-view-mode walk \fP(Shortcut: \fB\-walk\fP)
+View the Klein bottle as if walking on its surface.
+.TP 8
+.B \-view-mode turn \fP(Shortcut: \fB\-turn\fP)
+View the Klein bottle while it turns in 4d.
+.TP 8
+.B \-view-mode walk-turn \fP(Shortcut: \fB\-walk-turn\fP)
+View the Klein bottle as if walking on its surface. Additionally, the
+Klein bottle turns around the true 4d planes (the xy, xz, and yz
+planes).
+.PP
+The following options determine whether orientation marks are shown on
+the Klein bottle.
+.TP 8
+.B \-orientation-marks
+Display orientation marks on the Klein bottle.
+.TP 8
+.B \-no-orientation-marks
+Don't display orientation marks on the Klein bottle (default).
+.PP
+The following three options are mutually exclusive. They determine
+how the Klein bottle is projected from 3d to 2d (i.e., to the screen).
+.TP 8
+.B \-projection-3d random
+Project the Klein bottle from 3d to 2d using a random projection mode
+(default).
+.TP 8
+.B \-projection-3d perspective \fP(Shortcut: \fB\-perspective-3d\fP)
+Project the Klein bottle from 3d to 2d using a perspective projection.
+.TP 8
+.B \-projection-3d orthographic \fP(Shortcut: \fB\-orthographic-3d\fP)
+Project the Klein bottle from 3d to 2d using an orthographic
+projection.
+.PP
+The following three options are mutually exclusive. They determine
+how the Klein bottle is projected from 4d to 3d.
+.TP 8
+.B \-projection-4d random
+Project the Klein bottle from 4d to 3d using a random projection mode
+(default).
+.TP 8
+.B \-projection-4d perspective \fP(Shortcut: \fB\-perspective-4d\fP)
+Project the Klein bottle from 4d to 3d using a perspective projection.
+.TP 8
+.B \-projection-4d orthographic \fP(Shortcut: \fB\-orthographic-4d\fP)
+Project the Klein bottle from 4d to 3d using an orthographic
+projection.
+.PP
+The following six options determine the rotation speed of the Klein
+bottle around the six possible hyperplanes. The rotation speed is
+measured in degrees per frame. The speeds should be set to relatively
+small values, e.g., less than 4 in magnitude. In walk mode, all
+speeds are ignored. In walk-and-turn mode, the 3d rotation speeds are
+ignored (i.e., the wx, wy, and wz speeds). In walk-and-turn mode,
+smaller speeds must be used than in the turn mode to achieve a nice
+visualization. Therefore, in walk-and-turn mode the speeds you have
+selected are divided by 5 internally.
+.TP 8
+.B \-speed-wx \fIfloat\fP
+Rotation speed around the wx plane (default: 1.1).
+.TP 8
+.B \-speed-wy \fIfloat\fP
+Rotation speed around the wy plane (default: 1.3).
+.TP 8
+.B \-speed-wz \fIfloat\fP
+Rotation speed around the wz plane (default: 1.5).
+.TP 8
+.B \-speed-xy \fIfloat\fP
+Rotation speed around the xy plane (default: 1.7).
+.TP 8
+.B \-speed-xz \fIfloat\fP
+Rotation speed around the xz plane (default: 1.9).
+.TP 8
+.B \-speed-yz \fIfloat\fP
+Rotation speed around the yz plane (default: 2.1).
+.PP
+The following two options determine the walking speed and direction.
+.TP 8
+.B \-walk-direction \fIfloat\fP
+The walking direction is measured as an angle in degrees in the 2d
+square that forms the coordinate system of the surface of the Klein
+bottle (default: 7.0).
+.TP 8
+.B \-walk-speed \fIfloat\fP
+The walking speed is measured in percent of some sensible maximum
+speed (default: 20.0).
+.SH INTERACTION
+If you run this program in standalone mode in its turn mode, you can
+rotate the Klein bottle by dragging the mouse while pressing the left
+mouse button. This rotates the Klein bottle in 3D, i.e., around the
+wx, wy, and wz planes. If you press the shift key while dragging the
+mouse with the left button pressed the Klein bottle is rotated in 4D,
+i.e., around the xy, xz, and yz planes. To examine the Klein bottle
+at your leisure, it is best to set all speeds to 0. Otherwise, the
+Klein bottle will rotate while the left mouse button is not pressed.
+This kind of interaction is not available in the two walk modes.