4 wire fan and i'm not sure what to do about the blue and yellow wires

I have acquired some old server fans for a project and while red and black are obvious, I'm not sure what to the blue and yellow wires are for. I'm guessing speed control and temperature sensor. It's a NMB-MAT fan, model 3615ml-04w-B76. I'd love to be able to use these two functions or what ever they are, but I have no clue about how to go about getting the information. google searches for the part and model number haven't yielded any useable results. please help a poor newb out.

PC fans have a well-defined standard. Nobody reads the standard, of course. Search for "standard 4-wire fan" or something like that.

One wire is PWM control. It can be left open and the fan will run at full speed. The other is a tachometer for speed feedback. One pulse per revolution.