Specification of the Crystallographic Binary File (CBF/imgCIF)

Abstract

The Crystallographic Binary File (CBF) is an electronic file supporting the efficient storage of large quantities of experimental data in a self-describing binary format. Its primary function is to handle large image data sets within laboratories and for interchange between collaborating groups. Except for embedded binary data segments, the format is derived from that of the pure-ASCII Crystallographic Information File (CIF), so that all suitable CIF data items describing the crystallographic experiment and description of any structural results may be included. Embedding of binary data fields makes use of Internet standard MIME headers to facilitate the identification and handling of separate binary components. Where file size or efficiency of processing are not important, the embedded binary data may be ASCII-encoded according to a specified protocol. The resultant file, containing only ASCII character data, is fully compatible with CIF and is known as an image-supporting crystallographic information file (imgCIF). This chapter describes in detail the structure and format of CBF and imgCIF representations, and explains how to convert from one format to the other. This chapter is also available as HTML from the International Tables Online site hosted by the IUCr.