A collection of objects. One way to understand this data type is to consider that a normal object can be a single value or a time sequence. For example if you have a movie, this is a time sequence of Bitmap variables. But what if you want a time sequence of time sequences of a bitmap. One way that this can come up is when you are looking at the output of a DataTask. Here you have a collection (that is a time series) of results, but each result could be a time sequence of entries. This is a time sequence of time sequences, and rather than creating something that supports only that, the Variable Set mechanism is more general.