The Broad System of Ordering (BSO), a subject-indication coding and ordering scheme developed to meet the requirements of the UNISIST program for an international switching mechanism between information systems using diverse indexing/retrieval languages is described. The scope and purpose of the BSO, its development and testing, a schematic outline of the schedule, and an explanation of its main features (facet design, treatment of composite subjects, notation, and alphabetical index) are presented. The report concludes with a brief review of future needs and prospects for the new ordering system. (Author/RAO)