The purpose of this guide is to advise on the principles of good practice in the use of ATLAS for the writing of test procedures. This advice has been drawn from practical applications in many organizations. A number of companies are contractually committed to prepare test procedures in ATLAS, a system which must be unambiguously interpreted by both personnel and machines. The experiences of test engineers from these companies have been distilled to prepare this guide. Since ATLAS must be capable of communicating complex test requirements, the language has a large vocabulary and complex syntax. Therefore, it is not always readily understandable. Herein lies the need for this guide. The guide concentrates on the proper use of the ATLAS vocabulary, syntax, and structure for the generation of unambiguous test procedures. If the guide assists in the preparation of good test procedures, it should also assist in the writing of computer programs which will efficiently process ATLAS test procedures for automatic implementation.