CCSD3ZF0000100000001NJPL3IF0PDS200000001 = SFDU_LABEL
RECORD_TYPE             = STREAM
PRODUCT_CREATION_TIME   = 1992-05-13
OBJECT                  = TEXT
NOTE                    = "Description of Planetary Science Data
Dictionary tables."
END_OBJECT              = TEXT
END


THE PLANETARY SCIENCE DATA DICTIONARY

DELIMITED ASCII FORMAT


This text accompanies a number of delimited-ASCII tables that 
form the bulk of the Planetary Science Data Dictionary.  These 
tables are designed to be bulk-loaded into any relational 
database management system.  The table descriptions include 
logical links that should be created between tables, so that key 
information may remain consistent.

The Planetary Science Data Dictionary is a single, logical 
database of information, however, we have split it into two 
sections.  The first part, the Data Element Database, contains 
descriptions of individual data elements (or attributes, or 
descriptors) that are used to describe science data products.  
The key to almost every table in this database is the Column name 
(or data element name).

The second part of the Planetary Science Data Dictionary 
identifies and describes what we call Data Objects.  Objects can 
be data structures like image, table, or spectrum; catalog 
structures like a database table; or physical entities like 
spacecraft instruments.  The objects described in this set of 
tables contain lists of attributes that are required for 
describing the object, and others that are optional descriptors.  
This helps us standardize the way things are described in our 
catalog, and it helps us validate the structure of data 
descriptions.


----

THE DATA ELEMENT DATABASE


COLTN  (column name/terse name) contains status information for 
each data element.  This is the master table of the data element 
database.  It is linked to each of the other tables in a one-to-
many relationship.

Column name
Terse name
General data type
Unit
Standard value type
Standard value key
Maximum
Minimum
Maximum length
Minimum length
Date last changed

------

CDESC (column description) is linked to COLTN by Column name, and 
lists the descriptions for each data element name split up into 
numbered, 60-character lines.


Column name
Sequence number
Description

------

STDVALS (Standard values) is linked to COLTN by Column name, and 
lists each standard value associated with its data element name. 
We do not use the output flag yet -- it is designed to help in 
the creation of a printed data dictionary document.


Column name
Standard value
Output flag

------

INDKEY (Index key) is linked to COLTN by Column name.  It assigns 
each data element one or more general classifications.  This is 
meant to help a user obtain collections of data elements that 
pertain to particular types of data products.


Column name
Index classification

-----

UNIT is linked to COLTN by Unit.  It is a list of units of 
measurement.

Symbol
Unit name
Measured quantity

-----

CALIAS  (Column alias) shows each alias associated with a data 
element, and the objects in which aliasing is allowed.

Data element name
Alias
Object  

-----

ATTROBJ (Attribute/object) shows in which object each data 
element appears, and whether or not it is a required descriptor

Column name
Required flag
Object name



THE OBJECT DATABASE

OBJECTS  contains basic information about each data object.  This 
is the master table of the Objects database.  It is linked to 
each of the other tables in a one-to-many relationship.

Object name
Object terse name
Status type
Source name
Definition date
Object type

-----

OBJDESC (Object description) is linked to OBJECTS by Object name, 
and lists the descriptions for each object name split up into 
numbered, 60-character lines.

Object name
Sequence number
Description

-----

OBJHIER (Object hierarchy) is linked to OBJECTS by Object name, 
and tracks all hierarchical relationships between objects.  Some 
objects are required to describe other objects -- the Column 
Object is required to describe a Table, for example.  Other 
objects are optional.

Object name
Required flag
Subobject name

-----

OBJATTR (Object/Attribute) is linked to OBJECTS by Object name.  
It is a mirror image of the ATTROBJ table in the data element 
database.   It shows the data elements that appear in each 
object, and indicates whether or not the data element is a 
required descriptor.  (This table duplicates the other because we 
were unable to indicate many-to-many relationships on our PC-
based relational database system.  A more robust system would be 
able to use only one of these tables.)

Object name
Required flag
Column name

-----

OBJALIAS (Object alias) is linked to OBJECTS by Object name, and 
indicates any names that have been used previously for a 
particular data object

Object name
Alias name

-----

STATNOT (Object status note) is a table that allows the system 
managers to include notes on the objects provenance, progress or 
use in the system.  It is linked to OBJECTS by Object name, and 
lists the status notes for each object name split up into 
numbered, 60-character lines.

Object name
Sequence number
Status note
