Since we are on the topic of scanning, I thought I would add in a bit:
When scanning conventional channels are trunked talkgroups, you can scan all of the channels/groups in the frequency (or group) set. Up to the set's maximum of 1024. Why would you? That's your business. But the radios hardware will allow it.
Getting more than sixteen on the knob is easy, and has been possible since the M-PA days of the 1980's. You simply swap the Groups on the Knob for Systems, and remap the System UP & DOWN buttons for GROUP UP and GROUP DOWN functions. To allow more than 16 SYSTEMS on the knob now that you have moved it, map an unused OPTION BUTTON for SYSUP and enable RAMP WRAP under KEYPAD OPTIONS.
Finally, when it comes to scan options, you have three ways you can do it: FIXED, PROGRAMMABLE AND LIMITED.
FIXED is just what it says. The radio's scan list is locked by the programming, and cannot be altered by the user.
PROGRAMMABLE is the more popular option, and allows the user full editing privileges of the radio's scan list, and "remembers" the setting though a power cycle.
LIMITED is the most underused option. It allows the user full editing privileges of the radio's scan list, but DOES NOT "remember" the setting though a power cycle, and will always revert back to the originally programming scan list settings after a power cycle.
TRIVIA:
Ever notice when you program a radio, you will see on the Computer's display "...programming fixed personality" then shortly afterward "...programming variable personality" ?
When you first program a radio, the fixed and variable personality files are identical. Mirror images of each other.
When the user edits anything, they alter the VARIABLE personality file. The Fixed stays intact.
This FIXED personality file handles several functions. When the radio is DYNAMICALLY REGROUPED to new data (for a special event, etc.), it uses the new data transmitted to it over the air. When the radio is DYNAMICALLY UNGROUPED (or reverted to normal), it uses the Fixed Personality data to get back were it belongs. Another function of the Fixed personality data is in the LIMITED scan list, to revert the radio back to original data during a power cycle.
My humble 2¢ worth....