It's true, you can't tell from the frequency itself if a channel is
"narrowband". A UHF MPT-1327 in my area uses narrowband
analog voice (11kHz BW), 6.25kHz steps (likely for future channel
assignments), but some of the frequencies are 451.5000,
451.6000 etc. Many are on 12.5kHz grid, and none on the 6.25kHz
grid (yet). I have seen in the database some UHF LTR systems
using 6.25kHz frequencies e.g. 451.30625.
Dave