Alright.
Its a little hard to understand until your in front of one with somebody who knows how to use it.
But here it is:
If you load one sample like an organ, into the asr, you select the "root key" and thats where the main sample will be. Every key above it goes a note higher. Every key below it goes a note lower. But if instead of makin a new instrument, you wanna put another sound into the asr, accessible at the same time as the organ, the when you select the root key of your next sound (maybe a piano)(say you selected it 10 keys above the organs root key), it will only take up half the keybord. So itll share with the organ. It will split the difference in half. So if you have 10 keys between the piano and the organ roots, each instrument will only go 5 keys until it crosses into the next instrument. You understand? Its easy to get once your workin with one and its a lot easier than it sounds.