A Data File consists of a collection of Data Series that have the
same origin. EMG data is often collected from a number of muscle sites,
resulting in files containing multiple channels of data (where each channel is
represented by a Data Series). It is also common that the same analysis is
desired for all of the channels. The Data File was created for this reason. It
allows Data Series to be organized together, and it allows operations to be
performed on all of the Data Series that it contains.