"The thesaurus comprises two parts. The first arranges the descriptors by subject fields in an introductory general scheme. The second part of the thesaurus contains an alphabetical list of descriptors. The thesaurus is a documentation language devised for the purpose of analysing works, articles, reports and other documents referring to the problems of mass communication according to the particular medium to which they refer: books, the press, records, films, radio or television. While its main purpose is to characterize the information in a sufficiently precise manner to allow post-storage retrieval of the documents containing it, it has the secondary purpose of enabling queries to be expressed in a form which will match the information available. In addition, by providing a valid basis for the exchange of data between documentation systems, it will allow national or international networks to operate in a fully satisfactory consistent manner. In the social sciences and the humanities there are still relatively few fields in which a documentation language has been tried out in a systematic manner. A thesaurus on communication can reasonably be expected to make a contribution to scientific communication, and it would be a pity if full use were not made of the facilities it provides in this regard to both research workers and practicians, in a sector which social changes have brought particularly to the fore."