Most of this Rule is very technical and only of interest to equipment and ship designers. However, it is probably worth reading as background information. It is also interesting to realise how precise the people who drew up these rules were!

There are a few points which help with identifying light combinations at an advanced level.

Part (h), tells us that the coloured side lights will always be below the masthead lights. That is one of the reasons why a sailing vessel which leaves its tricolour light on when it begins to motor, and only adds its white masthead light is not complying with these Rules.

Of course, they would also be indicating they were a fishing vessel, the type dependent on which side you are looking at!

This point can aid identifying the purpose of different lights when you are uncertain of the class a vessel you are observing.

Part 9, limits the angles that lights can show through. It is a point worth checking on your own vessel. It is very common, especially in small craft to see lights showing through the wrong angle because they have been displaced by the stress of wind or waves in heavy weather. This can make life very difficult for other vessels when they are deciding how best to avoid a collision.