ANSI INCITS 39

Abstract

Scope.This standard provides specifications for format and recording for a l/2-inch (12.7-mm), 9-track magnetic tape to be used for information interchange among information processing systems, communication systems, and associated equipment utilizing a code for information interchange that was agreed upon by the interchange parties. This standard deals solely with recording on magnetic tape as described in American National Standard for Information Systems - Unrecorded Magnetic Tape for Information Interchange (9-Track 800 CPI, NRZI; 1600 CPI, PE; and 6250 CPI, GCR), ANSI X3.40-1983, where the following sections are dealt with in detail. general requirements, definitions, tape physical and magnetic requirements, and tape reel. Compliance with the standard for unrecorded tape is a requirement for information interchange. A standard on labeling, such as American National Standard Magnetic Tape Labels and File Structure for Information Interchange, ANSI X3.27-1978, may be used to support data interchange between data processing systems. CAUTION NOTICE: The user’s attention is called to the possibility that compliance with this standard may require use of an invention covered by patent rights. By publication of this standard, no position is taken with respect to the validity of this claim or of any patent rights in connection therewith. The patent holder has, however, filed a statement of willingness to grant a license under these rights on reasonable and nondiscriminatory terms and conditions to applicants desiring to obtain such a license. Details may be obtained from the publisher. No representation or warranty is made or implied that this is the only license that may be required to avoid infringement in the use of this standard. Purpose  This standard defines the requirements and supporting test methods necessary to ensure interchange at acceptable performance levels. It is distinct from a specification in that it delineates a minimum of restrictions consistent with compatibility in interchange transactions.  The performance levels contained in this standard represent the minimum acceptable levels of performance for interchange purposes. They therefore represent the performance levels that the interchanged items should meet or surpass during their useful life and thus define end-of-life criteria for interchange purposes. The performance levels in this standard are not intended to be employed as substitutes for purchase specifications.  Wherever feasible, quantitative performance levels that shall be met or exceeded in order to comply with this standard are given. In all cases, including those in which quantitative limits for requirements falling within the scope of this standard are left to agreement between interchange parties, standard test methods and measurement procedures shall be used to determine such limits.  U.S. engineering units are the original dimensions in this standard. Conversions of toleranced dimensions from customary U.S. engineering units (similar to British Imperial Units) to SI units have been incorporated in this standard according to Method A as described in American National Standard Metric Practice, ANSI/IEEE 268-1982, and in International Standard for Toleranced Dimensions - Conversion from Inches into Millimetres and Vice Versa, IS0 370-1975. Method A, as described in ANSI/IEEE 268-1982, should be used to achieve economy unless requirements for absolute assurance of fit justifies use of Method B. In the national standards of IS0 member nations, additional rounding may be done to produce “preferred” values. These values should lie within or close to the original tolerance. Except as indicated in 1.2.3, interchange parties complying with the applicable standards should be able to achieve compatibility without need for additional exchange of technical information.