This standard recommends procedures for analyzing documents, determining their content and selecting indexing terms. It is limited to the early stages of indexing and is independent of the practice of the indexing system, whether pre-coordinated or post-coordinated. Describes general methods of document analysis that should be applied in any situation. However, these methods are especially intended for indexing systems in which document subjects are expressed in abbreviated form using the terms of a controlled indexing language. In this context, the controlled language is generally constituted by a subset of terms extracted from natural language and structured, for example, by means of a thesaurus. These methods can typically be applied to systems in which, for retrieval purposes, concepts are represented by symbols selected from the classification scheme. 2 The techniques described in this standard can be used by any agency where human indexers are used to thematically analyze the document and express the content in the form of indexing terms. They are not applied in institutions that use automatic indexing techniques in which existing terms in texts are organized into sets or classes according to criteria that can be applied by a computer, for example, by frequency of appearance and/or adjacency in the text, although the purpose of these systems is the same. 3 This standard must, first of all, serve as a guide for indexers during the stages of document analysis and concept identification. It can also be applied to document search to transform user requests into controlled indexing terms. It can also serve as a guide for the preparation of analytical summaries, keeping in mind, however, that these tasks, although analogous, are not identical. 4 This standard is intended to promote the use of a standardized practice a) in an institution or a network of centers or institutions; b) in different indexing services, especially those that exchange bibliographic records.