XSN tac 4 used to be White-2, with the switch to Narrowband its now called VFIRE22, no longer TAC4, also Tac-6 has been renamed to CALCORD. Tac-10 is a calfire tac channel. For whatever reason redcom way back when, decided to go away from using common naming conventions for common mutual aid channels. It appears they are now going back to using common channel names.
Here is a link to the narrowband channel lineup: