Smoke Signals

As ubiquitous as smoke signals have been in the lore of Western USA communications between and among various groups of Native Americans, does anybody have any clue how these things worked (maybe still work)?

I have seen some old Boy Scout manuals showing a dozen or so “messages” that could be sent with smoke, or by way of stacked rocks or twisted grass or some other trail marking techniques.

But how much data can be transferred in smoke?

As I understand it smoke signals were not a uniform method for sending a message. The climatic restrictions alone forbade it in many instances. But in all, smoke signals were usually a known signal between sender and reciever…