The shader that is presented here basically takes as input a set of uv coordinates and produces a set of rectangles, each with their own uv coordinates. These rectangles are randomly distributed and rotated and do not necessarily cover everything: the fac output signals whether there is a rectangle or not.
With this set-up you can for instance cover a surface with random hull plates or similar:
The noodle used to produce the image looks like this:
There are two OSL shaders in this noodle: the first one on the left is called Greebles and is the one that divides up the coordinate space, the second one is called Rivets and is part of the green Rivets material layout. That last one simply distributes small circles around the edges of a rectangle.
Both shaders are available on GitHub, Greebles here, and Rivets here.