Reason I ask, is analog FM had all sorts of sideband streams for the longest time, like SCA audio and DirectBand digital, that weren't well known at the time. And while internet access is certainly easier to get these days, there might still be a justification for one-way data broadcasts in certain applications, so I wonder if someone's out there leasing subchannels or sub-packet-IDs or what-not, and shuffling encrypted data around in them.