| Quick-Start Introduction to PDS Archiving |
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Volume Files
If the data set to be delivered is non-trivial in number of files, then
it will be packaged as a volume - a set of files intended to be
distributed together. The volume collects and organizes the data files,
labels, catalog files, software, documentation and all other supporting
information into a standardized logical hierarchy. This organization
resembles the natural organization the data set would have on a random-access
medium like a CD-ROM disk, but the structure of the hierarchy is internally
documented so that even when stored on a serial medium like tape it can be
reproduced.
The relationship between logical volumes and physical media can be 1:1, 1:N
or N:1. Chapter 19
of the PDS Standards Reference details the volume
organization and required directory structure for each situation.
Required Files by Subdirectory
Following is a list of the
additional files required by PDS to document the contents of the volume,
broken down by volume subdirectory.
Listed are only those subdirectories and files that are either required
outright or extremely unlikely to be empty (and thus omitted).
The PDS Standards Reference has a complete list of the optional subdirectories
and the files which must be included in those directories when they are present.
(As you might expect, if the subdirectory is not present in the volume then
its required files are also absent.)
The ".TXT" suffix denotes a plain ASCII text file. These files will have
a minimal attached PDS label (using the TEXT object) for use in automated
processing.
The ".CAT" suffix denotes an ODL file containing a PDS catalog object -
follow the link for details and blank templates.
- Root Directory
- The highest-level directory on the medium
- AAREADME.TXT
- A general introduction to the volume
- VOLDESC.CAT
- An ODL file containing the VOLUME object describing this volume
- INDEX Subdirectory
- PDS requires at least a minimal index of file names, directories and
basic parameters.
Any other indices which are useful for working with the data should
also be included here.
- INDXINFO.TXT
- General description of the contents of the INDEX subdirectory
- CUMINDEX.TAB, CUMINDEX.LBL
- If there is more than one volume in the data set, a cumulative
index is required. These files are the cumulative index table
and corresponding PDS label. The INDEX.TAB file is described
using an INDEX_TABLE object, which is a specific instance of
a TABLE object reserved for use in volume INDEX
directories. The format and content requirements on the
INDEX_TABLE object are described in
Appendix A
of the PDS Standards Reference.
- INDEX.TAB, INDEX.LBL
- Volume index file and PDS label, respectively. The index is
described by an INDEX_TABLE object.
- CATALOG Subdirectory
- In this subdirectory are collected all the catalog object files that
you created to describe the data sets, instruments, targets, the mission,
and anything else that is in ODL and isn't a datafile label.
- CATINFO.TXT
- A description of the contents of the CATALOG subdirectory
- CATALOG.CAT
- This file contains the CATALOG object, which is used to tie together
all the catalog object files produced in documenting these data
(i.e., the MISSION, INSTRUMENT, DATA_SET_COLLECTION, etc. catalog
files).
- DOCUMENT Subdirectory
- This contains any and all text files describing any aspect of the
observations comprising the data set, from instrument specs to
reduction techniques. If there are none it may be omitted.
- DOCINFO.TXT
- A description of the contents of the DOCUMENT directory.
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