As it stands now, you can only listen to a system at a time, wether by knob position or zone.
In the proposed new firmware, you should be able to listen to more than one system, regardles of knob/zone (?).
For example, you might listen to your state police. They usually have their own system.
Then, you might also like to listen to your county sheriff. They might have their own system.
And finally, you migt also like to listen in to your local police department, and, you've guessed it, they might own their own system as well.
You will need to program the frequencies of all of those systems.
Then program all of the talkgroups you would like to listen from any of those systems.
Finally, you would choose a knob position to program all of those different talkgroups, from any or all of those systems, and tell the radio you want to do a multiple system scan ( or whatever name Unication would end up naming that on the finished firmware update).
A system, is a group of repeaters, carrying voice/data, over a wide ranging area.
Some systems, by agreement, can carry this traffic to include multiple users.
Users can be other entities, for example, your state might have a big robust and expensive, wide area system and, in order to defray costs, might allow other smaller entitities to use it, such as, counties or cities.
Hope this helps...