The Crystallographic Information File (CIF) was introduced as a data exchange standard in crystallography in 1991 and has become embedded in the practice of single-crystal and powder diffractometry. Versions of CIF exist that describe macromolecular structure and diffraction images, so that CIF may be used anywhere in a data pipeline from image capture to publication in what has been called a 'coherent information flow' (also CIF!). In practice, slight differences in data model and file format have led to 'dialects' of CIF, which can coexist quite happily. However, there is a consequent barrier to full interoperability. A new version of the CIF format will allow the development of a new generation of CIF 'dictionaries' (the formal data description schemas or 'ontologies'). This will allow fully automatic interconversion between existing CIF data files in either formalism, but has the added bonus of providing a descriptive framework for any type of crystallographic information. Formally, the CIF approach makes no distinction between 'data' and 'metadata', and so is arbitrarily adaptable and extensible to any domain of structural science or further afield. Since the CIF format has a very simple syntactic structure which makes the contents very easy to read, CIF dictionaries can provide a simple template for developing new metadata schemas by working scientists who are not experts in informatics.