What is a local data dictionary?

A data dictionary defines the attributes and classes that may be used in PDS4 product labels to describe planetary data. It must contain definitions as well as the syntax and semantic constrains placed on values of attributes. For classes, it provides the explicit list of attributes defining the class and indicates which are required, optional, and repeatable.

A local data dictionary is a dictionary that is discipline- or mission-specific.

All PDS archives are based on the common dictionary (the pds namespace) and they may also include classes and attributes defined in one or more local data dictionaries. LD3 Tool is a web-based application for designing local data dictionaries.