Various models of ProxySG (e.g. 810-5 and 810-10) have different user limits. What is a user
limit?

A.
The number of unique IP addresses is not different for the both models, but there is a strictly
enforced limit of simultaneous TCP connections that each model supports

B.
User limit is the recommended number of unique IP addresses that can connect to the
ProxySG for the given hardware. ProxySG can be configured to exceed this limit.

C.
It is the number of unique IP addresses that can connect to the ProxySG, and this limit is strictly
enforced by the license.

Explanation:
https://support.bluecoat.com/sgos/ProxySG//Mobile/Advanced/Content/02Tasks/Traffic
_Management/user_overflow_actions.htm