program SILKE NXDN (Ca. Butte County)

As I was monitoring the Silke system in Butte County, my BCD536 (on screen) was in ID search. It stopped on a 5 or 6 digit number (transmission), also on the lower left of the screen was "base 2".

I'm not sure what this means. Does it require special programming to effectively monitor that particular user ID?

Didn't you already ask this?

It's just part of NXDN systems. If a name is available it will be displayed. There is no way to monitor a system by radio ID, only talk group.