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In many episodes of Star Trek: TNG, people on a planet (or somewhere away from the Enterprise) transport back to their ship by someone tapping his/her communicator and saying "3 to beam up" or similar. Then, the 3 people intended by that person almost immediately begin beam-out.
How does this work? It often happens that the "N" people intended for transport are a subset of all the people available. I thought perhaps it has to do with the stances of those N people, but that seems unlikely. It also occurred to me that the computer could sense the thoughts of the person to figure out which people he/she means, but this is even more far-fetched, and has never been supported by any technobabble on the show.
There was one time someone says something like "2 people and one piece of equipment to beam up" (I don't remember which episode). That made somewhat more sense, as the transporter chief could probably see via targeting scanners exactly which thing was the "piece of equipment" but it still leaves the question of which people to beam up fuzzy.
Anyone have other ideas? This has always bugged me much more than other seeming weirdnesses on TNG, which I am usually able to come up with headcanon theories for.