The last couple of weeks, a few TV trade magazines have been abuzz about something that’s old news to us free-TV enthusiasts: There are a growing number of digital subchannels available in markets all over the country. For over-the-air TV viewers, it’s like having a virtual pay-TV system except without the paying. The most remarkable thing about this burgeoning free entertainment menu is that few people seem to know about it.

A side note: What’s the best name for these digital TV subchannels? Michael Malone tackled that question in Broadcasting & Cable. “The channels are alternately referred to as diginets or multicast nets or dot-two channels or subchannels, creating confusion among viewers, and even industry types,” he wrote. Katz Broadcasting promotes the term “emerging broadcast networks,” but I think that’s an unwieldy mess. Headline writers seem to prefer “diginets,” but I like “dot-twos” because it describes how to find these networks, even those that are really at dot-three or dot-seven.

I’ve been watching dot-twos since The Tube and Universal Sports were on. (The Tube faded to black in 2007 and Universal Sports shifted to pay-TV distribution in 2012.) This happy by-product of the digital TV conversion has exploded since then. Of the 70 channels I can pick up here in Denver, 42 are dot-twos, and they include channels devoted to movies, classic TV, news and weather. Sure they also include a solid chunk of stuff I can do without – religion, shopping, and Spanish-language programming – but it’s nice to have something for everybody.

What hasn’t changed since the dot-twos’ early days is that few viewers are aware of them. (I couldn’t find any dot-two surveys, but almost no one I talk to knows about them.) You might say that you can’t pay for this stuff; only a handful of dot-twos are on cable systems, and none are on Dish Network or DirecTV. The only way to watch is over the air, which is great for cord-cutters and a little inconvenient for everyone else.

So why not put together some advertising to let viewers know what they might be missing? This could be a great way for broadcasters as a group to boast about another facet of their public service. At a time when it’s hard to find a movie on the major broadcast TV channels, wouldn’t it be a good idea to mention that there are over 100 movies available every week on these dot-twos? As wireless companies clamor for TV’s bandwidth, wouldn’t it be smart to show America that it’s already being put to good use?