Oh, could be. They did at least some C15s sold as the "Centurion C15" with a CIA prefix. For their official name, Century International Arms.
These were still made in someone else's factory (Olympic?) but was a custom run so Century got their own serials. Yes, sure, could be "Century Arms T-word" to be a different series for their own ID or just to allow a separate numerical series (a thing that happens for serials).
Found some lists of AR-15 serial ranges, but none with CAT in them yet.