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From the Planetary Data System’s Quick-Start Introduction to PDS Archiving
PDS labels are written in the Object Description Language (ODL), as are all PDS catalog files. ODL consists of a series of lines of the form “keyword = value”, with certain keywords (for example,OBJECT) being used to delimit structures within the label. PDS prefers to use non-cryptic keywords, so that the data labels are more easily interpreted by users browsing through them.
This library provides a python interface to PDS files. It parses a data product’s attached labels into a parse tree of dictionaries which maintain structure. It also provides convenient methods to extract image data from a data product with attached labels.
The [pds.core.reader] module is the lowest level software stack. It generates a tuple for all (keyword, value) pairs. This module preforms some preprocessing on the data by stripping blank lines and comments.
The pds.core.parser module consumes these tuples and adds information the parse tree. It is within this module that type conversion should performed, as well as any other transformation on the labels.
The pds.imageextractor module provides a convenient way to extract images from PDS data products. Use of this module keeps the parsing details and knowledge of the PDS specification under the hood.