This part of ISO/IEC 12087 facilitates the interchange of digital images. For this purpose, conceptual, architectural, and functional definitions of the Image Interchange Facility (IPI-IIF) are established. ISO/IEC 12087-3 consists of two major parts, the: a) IIF data format (IIF-DF) definition (by means of a formal syntax, described according to the Abstract Syntax Notation One) (ASN. 1) -- refer to clause 5), and the b) IIF Gateway definition (by means of a manual page description of the functionality of an Application Program Interface) (API) -- refer to clause 7.