| Quick-Start Introduction to PDS Archiving |
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PDS Archive Structure and Elements
The term PDS archive is most often used to refer to a specific subset
of the entire PDS collection - for example, all the files submitted by a
particular mission.
In this popular sense, then,
a PDS archive is a set of files arranged in a hierarchy in which each
level up the hierarchy provides documentation on a broader scale.
Following is a very general description of the essential levels.
- Data Files
- The lowest level is that of the data files themselves. At this level
each file will have a PDS label either appended to the beginning of
the file or, more often, in a separate but proximate file. "One file,
one label" is the general rule.
- Meta-data Files
- At the intermediate level are files which describe the circumstances
and parameters of the data collection (for example: the instrument used,
the observatory site, the type of data collected, etc.). These files
are called "catalog objects" or just "catalog" files.
- Volume Description Files
- These files are included on any distribution medium intended to be an
entire, self-contained archive - for example, a set of DVDs
or a ZIP file.
The volume description
files detail the organization of the data in the archive (in terms of
directories, e.g.) and any additional documentation and software which
might be included.
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