ISO 25577:2013 specifies the requirements for a generalized XML-based exchange format for bibliographic records as well as other types of metadata. It does not define the length or the content of individual records and does not assign any meaning to tags, indicators, or identifiers, these specifications being the functions of an implementation format. ISO 25577:2013 describes a generalized structure, a framework designed primarily for communication between data processing systems, but can also be relevant for use as a processing format within systems.