->ENCODER function takes a list of points and encode them in a single encoder. Each point is a list of ( timestamp, latitude, longitude, elevation, value ). Since 2.1.1, a point can also be a Geo Time Series™ or a wrapped one. In that case all the points of the Geo Time Series™ are added to the encoder.
An encoder is very similar to a Geo Time Series™, it differs by its ability to store values of all four types (LONG, DOUBLE, BOOLEAN, STRING) where a GTS is limited to the type of the first value stored. An encoder can also have a name, labels and attributes.
The set of operations which can be performed on encoders is more limited than those that can be performed on GTS.