The reduced ion mode data sweeps are stored in single orbit IEEE binary data files which have been organized into 100 orbit subdirectories. Furthermore, each of those directories is divided into a DATA sub-directory and an UNCERT sub-directory, containing the data and the data uncertainties, respectively. This directory also contains the description of the reduced ion mode data sweeps in the file DATASET.TXT. The /DATA directory contains a description of the ORPA instrument. The /DOCUMENT directory contains full reproductions of all these documents. The PDS catalog templates associated with this dataset are located in the CATALOG directory off the root of this CD-ROM in the file called "*.CAT".