3.5.1 The heading of the ship should be indicated
by a continuous line on the display with a maximum error of not greater
than ± 1°. The thickness of the displayed heading line
should not be greater than 0.5 measured at maximum range at the edge
of the radar display. The heading line should extend from the trace
origin to the edge of the display.
3.5.2 Provision should be made to switch off the
heading indicator by a device which cannot be left in the "heading
line off" position.
3.5.3 A heading marker should be displayed on
the bearing scale.