Specification of the Molecular Information File (MIF)

The Molecular Information File (MIF) is a data-exchange format for chemical structure utilising the STAR File format described in Chapter 2.1. The current implementation addresses the core requirements for representing a two-dimensional molecular structure, with limited facilities for describing stereochemistry and the molecular geometry at stereogenic centres. The approach is complementary to that of the crystallographic information file (CIF) but the two formats use different subsets of the full STAR syntax and are therefore not fully compatible. A brief historical review is given of the evolution of MIF from the concepts of the Standard Molecular Data format of the late 1980s. After an account of the file structure and syntax, examples are given of representing atoms, bonds and molecules; of the ability of the format to accommodate a variety of bond-type assignments (including the simultaneous description of bonding by different schemes); the mechanism for describing and managing structural templates (e.g. ligands, functional groups, amino-acid units etc.); and stereochemical descriptors. There is also an account of the use of MIF as a database-query language. Keywords: MIF specification; Molecular Information File specification; chemical structure; molecular structure; save frames; looped lists; data blocks; global blocks; bonding conventions; stereochemistry; stereogenic geometry