# How to determine how many dots are in a resource in a resource allocation graph?

I understand most concepts regard a resource allocation graph but I see that some resources have more dots (not sure what they are actually referred to) in them than others such as the example below, R1 and R3 have one dot, R2 has two dots and R4 has three dots. I cannot find anything online that explains this so I would just like to know, how would you determine how many dots should be in a resource when drawing the graph?

The dots represent the number of clients a resource can serve simultaneously. So, in the example in the question, resources $R_1$ and $R_3$ can only serve one client at a time, $R_2$ can serve two and $R_4$ can serve up to three clients at the same time.