But wait, there's more!
What does this do for me?
TrunkTracker IV with Control-Channel Only scanning and I-Call monitoring: Tracks voice traffic on P25, Motorola, EDACS, and LTR Trunked systems.
Is the version IV doing something even more?
The Triple Trunking was a catch phrase used for RadioShack scanners, and as correctly mentioned earlier in this thread, indicates the scanner works on LTR, Moto and EDACS systems. Newer digital scanners were called "Digital Trunking".
Uniden used the Trunktracker III as a catch phrase for it's line of analog trunking scanners that picked up the LTR, Moto and EDACS versions. (BC780, BCT15 etc.)
Trunktracker IV referred to digital scanners, including the BC796D, BCD996T/XT and the 396T/XT and others, the fourth mode was P25.
Even though the BC785 picked up digital, it was considered and labeled as a Trunktracker III since it only received Type II digital systems (with 3600 baud control data), not P25. (P25 systems use a 9600 baud control data signal)