Guys, don't get too hung up on the format of the dx.json file. It's all subject to change when the label code gets rewritten. The last element is a list of options. Right now that mostly means what colors are used for the label. See the variables "types_s" and "type_colors" in openwebrx.js See also the code in dx.c that does the read/write of dx.json on the server side.

The meanings are:
(none) cyan "active", i.e. station that has been heard on this Kiwi
WL red watchlist, station that has not been heard on this Kiwi
SB green sub-band, e.g. WSPR
DG lav. DGPS
NoN violet not currently used
XX violet interference
PB n/a has custom passband, not currently used
o n/a carrier offset (Hz) for NDB beacons