An Aggregation Server is a DODS client/server pair that allow a multi-file data set to look like a single file.
Consider the WOCE TOPEX sea height data set. It is actually a 3-d data set - longitude, latitude and time, but it is presented as a number of 2-d files.
The Aggregation Server will allow the user to request a 3-d chunk
out of this data set exactly as though it were a 3-d NetCDF file.