Band and frequency have to agree — the log, every award and every upload
are read on the BAND — and an operator fixing a wrong frequency is not
also expecting to fix the band by hand. That is exactly how a QSO ends
up filed on 20m at 7 MHz. Both sides follow, TX and RX.
Only when the number lands in a known allocation, because half a
frequency is typed on the way to all of it and a band must never be
blanked by that. bandForMHz moves out of App.tsx into lib/bandplan,
where the two callers can share one answer instead of drifting.
The band maps carried one hard-coded table — Region 1's — so a US operator's
40 m stopped at 7200 with stations spotted at 7250 hanging past the top of the
map, and the SSB wash started 25 kHz early. The region is a station-level fact
stated once (Settings → General, portable pref); lib/bandplan owns the three
tables and publishes changes to the open maps the way the distance unit reaches
the grids.
The tables stay deliberately coarse: a band map's wash is context, not a
regulatory chart, so only the differences an operator notices are split out —
Region 2's 80 m to 4000 and 40 m to 7300 (phone from 7125), Region 3's 80 m to
3900, the wider VHF/UHF allocations. National fine print does not belong in a
background tint.
rouggy