2017 Emmys: Outstanding Television Movie?

So, the 2017 Emmys nominations are out, and Black Mirror is nominated in the Outstanding Television Movie category. I'm glad it's nominated. Now, I couldn't see if it was just a specific episode, but regardless, isn't it considered if not a series, a limited series?

For me, this is an odd placement. Was there not enought room in the other categories, so they had to just put it somewhere (À la The Martian for Comedy in the Golden Globes). Or are they not sure where to put it, because of the anthology structure?