Committed Access Rate definitions question

Hello,

I'm trying to use CAR (Committed Access Rate) on my Cisco router and cannot understand the difference between an average rate, normal burst size and excess burst size. What's the difference?

I want some of my users to have a transfer rate limited to 1Mbs. I'm using that:

rate-limit output access-group 10 1000000 1000000 1000000 conform-action transmit exceed-action drop access-list 10 permit 10.1.10.0 0.0.0.255

(all 10.1.10.0 subnetwork should have that limit)

Is this correct? Because I got very strange results...