As Michael Gorman stated on many occasions (Gorman, 2003), MARC and ISBD are two sides of the same coin: the first technological, the second bibliographic. MARC was designed in the early 1960s by the Library of Congress and ISBD was conceived in the late 1960s in the context of IFLA (Guerrini and Possemato, 2015). Let's look at each.

6.1 MARC, UNIMARC, MARC21

MARC is a machine-readable format for recording and exchanging bibliographic data. In the early 1960s, the Library of Congress decided to convert its card catalogues into electronic catalogues, introducing the possibility of disseminating data also in digital format. In 1964 a team coordinated by Henriette Avram was asked to create a draft of a machine-readable record. This initiative led to the MARC Pilot Project, which involved 16 libraries of various kinds that worked on the creation and distribution of digital bibliographic data and the evaluation of the possible uses of the data produced by the Library of Congress (Library of Congress, Information Systems Office, 1968). The experimentation resulted in a format, called MARC I, which contained, in a nutshell, some characteristics of the current one. The work proceeded in collaboration with the British Library and in 1968 the MARC II format was presented and used as a model for subsequent formats.

In the 1970s MARC spread rapidly with the diffusion of automation in libraries. The USA tried to standardise the various formats by creating the USMARC Format for Bibliographic Data; however, several national and international variants emerged (e.g. INTERMARC in France and Belgium, later replaced by UNIMARC in France; CANMARC in Canada; UKMARC in England; ANNAMARC in Italy; RUSMARC in Russia). In 1999 MARC21 was published as a result of the collaboration between the Library of Congress, the British Library and the National Library of Canada to adopt a single format for the whole Anglo-American world. MARC21 is maintained by the Library of Congress.

MARC is very significant, because it is still able to manage highly formalised data and is used by the majority of libraries around the world.

In 1973 the general structure for transmitting MARC became the international standard ISO 2709. A record that conforms to ISO 2709 consists of three parts:

• 1 the first part is called the leader, which contains in encoded form general data for the processing of the record