The API docs do provide more detail for some of this stuff:http://www.lejos.org/nxt/nxj/api/lejos/ ... MODE_INPUT
If you are looking at those constants and methods it looks like you are trying to do something pretty low level, in which case you may have to dig through the source code to understand things fully. Most users will not be using those constants (which is why they are not in the tutorial etc.).
What is it you are trying to do?