what is self.cursor

I am very much a newb, please bear with me. I have a two whole scripts on the completed side of my wish list.

Now I am studying up on addins, because they seem to have some mouse functionality I desire in my next project. In studying the sample codes I have come across these lines in several examples:

def __init__(self):
self.enabled = True
self.cursor = 3

What is "self.cursor" and what do the values correspond to? I have seen it set to 1, 3 and 5.

Thanks,