What are the semantics of colors, numerical values and shapes?

[mstevens83]

I'm relatively new (OK, very new) to the world of Rx. The marble diagrams are certainly helpful but I often get confused by them. What tends to throw me off is that it is unclear to me with the semantics are of the differences in colour and numerical value of the marbles (and also of the different shapes used in rx diagrams elsewhere). See for example http://rxmarbles.com/#distinct or http://reactivex.io/RxJava/javadoc/rx/Observable.html#distinct(rx.functions.Func1).
I can't seem to find a simple explanation of what these attributes mean in terms of the events/items/objects being represented by the marbles.

My best guess is that the colour is an indication of an object's type/class and the number an indication of an object's state, but it might as well be the other way around (or entirely different). And where does that leave the shapes?

[mlamothe]

I'm just a user, but my understanding is that this project only uses one shape: circles.

As for colors, I believe they're essentially random just to make it easier on the eyes that having one uniform color.

The only real states shown on these diagrams is the completed state (shown by a short vertical bar) and the "result" observable line at the bottom of each diagram.

[ghost]

yes that would need documentation