Self defining Text Archive and Retrieval

The Self-Defining Text Archive and Retrieval (STAR) File, or simply the STAR File, is a text-based file format for storing structured data. It was proposed in 1991 by Sydney R. Hall. The format became widely used in molecular-structure sciences, although it is not specific to this field—it was designed as a universal approach to electronic data exchange and archiving.

One characteristic feature of the STAR File format is that data names (keys in key-value pairs) start with the underscore. They are separated from data values only by white space, for example:

_format "STAR File" _first_published 1991

The format was designed to provide a concise syntax for tabular data. The construct for this is called loop. Loops start with the loop_ keyword followed by names corresponding to columns and then by values.

loop_ _geom_bond_atom_site_label_1 _geom_bond_atom_site_label_2 _geom_bond_distance O1 C8 1.301(3) O1 Na1 2.161(2) O2 C36 1.425(4) O2 C39 1.425(4) O2 Na1 2.514(3) O3 C31 1.421(4) # ...

Using a "Dictionary Definition Language" file, itself a STAR File, STAR sub-formats can be defined for particular use cases. One notable STAR-based format is the Crystallographic Information File format.

The "STAR FILE" name is a registered trade mark of the International Union of Crystallography .