1、INCITS/ISO 4341-1978 (R1996)(formerly ANSI/ISO 4341-1978 (R1996) for Information Processing -Magnetic Tape Cassette andCartridge Labeling and File Structurefor Information InterchangeANSI/IS0 4341-1978 American National Standard for Information Processing - Magnetic Tape Cassette and Cartridge Label
2、ing and File Structure for Information Interchange Secretariat Computer and Business Equipment Manufacturers Association Approved May 25,1984 American National Standards Institute, Inc AmericanNationalStandardApproval of an American National Standard requires review by ANSI that therequirements for
3、due process, consensus, and other criteria for approval havebeen met by the standards developer.Consensus is established when, in the judgment of the ANSI Board of StandardsReview, substantial agreement has been reached by directly and materiallyaffected interests. Substantial agreement means much m
4、ore than a simplemajority, but not necessarily unanimity. Consensus requires that all views andobjections be considered, and that a concerted effort be made toward theirresolution.The use of American National Standards is completely voluntary; their existencedoes not in any respect preclude anyone,
5、whether he has approved the standardsor not, from manufacturing, marketing, purchasing, or using products, processes,or procedures not conforming to the standards.The American National Standards Institute does not develop standards and will inno circumstances give an interpretation of any American N
6、ational Standard.Moreover, no person shall have the right or authority to issue an interpretation ofan American National Standard in the name of the American National StandardsInstitute. Requests for interpretations should be addressed to the secretariat orsponsor whose name appears on the title pag
7、e of this standard.CAUTION NOTICE: This American National Standard may be revised orwithdrawn at any time. The procedures of the American National StandardsInstitute require that action be taken periodically to reaffirm, revise, or withdrawthis standard. Purchasers of American National Standards may
8、 receive currentinformation on all standards by calling or writing the American National StandardsInstitute.Published byAmerican National Standards Institute11 West 42nd Street, New York, New York 10036Copyright 1984 by Information Technology Industry Council (ITI)All rights reserved.These materials
9、 are subject to copyright claims of International Standardization Organization (ISO),American National Standards Institute (ANSI), and Information Technology Industry Council (ITI). Not forresale. No part of this publication may be reproduced in any form, including an electronic retrieval system,wit
10、hout the prior written permission of ITI. All requests pertaining to this standard should be submitted toITI, 1250 Eye Street NW, Washington, DC 20005.Printed in the United States of AmericaForeword (This Foreword is not part of American National Standard ANSI/IS0 4341-1978.) The International Organ
11、ization for Standardization (ISO) is a worldwide federation of national standards institutes (member bodies) that develops and publishes International Standards. The American National Standards Institute, Inc, is the American member of the ISO. The work of developing International Standards is carri
12、ed out through IS0 technical com- mittees. Every member body interested in a subject for which a technical committee has been set up has the right to be represented on that committee. International organizations, governmental and nongovernmental, in liaison with ISO, also take part in the work. Draf
13、t International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the IS0 Council. Whenever possible, an IS0 standard will be adopted to replace a comparable American National Standard to avoid dual st
14、andard situations that could result in incompatibility. It should be mentioned that certain conventions, spelling, and units in international stan- dards are different than those normally used in American National Standards, but are not expected to cause difficulty in understanding or use. Internati
15、onal Standard IS0 4341 was developed by Technical Committee ISO/TC 97, Computers and Information Processing, and was circulated to the member bodies in April 1976. It has been approved by the member bodies of the following countries: Australia Belgium Brazil Czechoslovakia Germany, FR Hungary Irelan
16、d Italy Japan Mexico Netherlands Philippines Romania South Africa, Rep of Sweden Switzerland Turkey United Kingdom USA No member body expressed disapproval of the document. Suggestions for improvement of this standard will be welcome. They should be sent to the Computer and Business Equipment Manufa
17、cturers Association, 3 11 First Street, NW, Suite 500, Washington, DC 20001. This standard was processed and approved for submittal to ANSI by American National Standards Committee on Information Processing Systems, X3. Committee approval of the standard does not necessarily imply that all committee
18、 members voted for its ap- proval. At the time it approved this standard, the X3 Committee had the following members: Edward Lohse, Chair William C. Rinehuls, Vice-Chair Catherine A. Kachurik, Administrative Secretary Organization Represented American Library Association. . . . . . . . . . . . . . .
19、 . . . . . . . . . . . . . American Nuclear Society. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AMP Incorporated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Association for Computing Machinery . . . . . . . . . . . . . . . . . . . . . . . Association of America
20、n Raihoads . . . . . . . . . . . . . . . . . . . . . . . . . . Association of the Institute for Certification of Computer Professionals. . . . AT b) the compact system, employing special data blocks with information content (labels), which are capable of being recorded using only numeric equipment;
21、c) the extended system, employing the magnetic tape labelling system specified in IS0 1001 together with new labels, to define a more comprehensive labelling system. This international Standard is not limited to the 3,81 mm magnetic tape cassette described in IS0 3407 but could also be applied to hi
22、gher capacity cassettes or cartridges. 2 REFERENCES IS0 646, 7-bit coded character set for information pro- cessing interchange. I SO 100 1, lnforma tion processing - Magnetic tape labelling and file structure for information interchange. IS0 3275, Information processing - Implementation of the 7-bi
23、t coded character set and its 7-bit and 8-bit extensions on 3.8 1 mm magnetic tape cassette for data interchange. IS0 3407, lnformafion processing - 3,81 mm (0.150 in) magnetic tape cassette for information interchange, 32 bpmm (800 bpi), phase encoded. 6 3 DEFINITIONS For the purposes of this Inter
24、national Standard the following terms have the meanings indicated. NOTE - For a better explanation, the concepts have, where appro- priate, been listed separately as logical and physical. The definition of a term that is used in an International Standard related to this subject conforms to its usage
25、 in that International Standard; the definition of a term that is in common use in a context related to this International Standard conforms to that common usage. Logical record : Related data treated as a unit of information. Physical block : A group of con- tiguously recorded charac- ters written
26、or read as a unit, and terminated with an interblock gap. file : A collection of infor- volume : A dismountable mation consisting of physical unit of storage records pertaining to a media, for example a single subject complete cassette con- Examples : In the context sisting of either of business dat
27、a, a payroll - two tracks used file, an inventory file. serially and sequen- - The delineation of a tially for data inter- file may be arbitrary. change as specified in IS0 3407 or - A file may be recorded on all or part of a track or volume, or on more than one volume. _ a single track (number 1, s
28、ide A) used serially for data interchange with the use of track number 2, side B, defined by agree- ment between the inter- change parties as spe- cified in IS0 3407 file section : That part of a file that is recorded on a single track of a cassette. - The sections of a file in a volume shall not ha
29、ve sections of other Files interspersed. File set : A collection of volume set : A collection one or more related files, of one or more volumes on recorded consecutively which one and only one on a volume set. file set is recorded. label : A block, at the beginning or at the end of a volume, of a tr
30、ack or of a file, that identifies, characterizes and/or delimits that volume, track or file. A label is not considered to be part of a file. label identifier : One or more characters recorded in the label to identify the label. characters used in a label : Only a subset of the characters of the 7-bi
31、t code defined in IS0 646 is used in the label. The allowable characters are described in the following way : - “n” characters : any numeric character from 0 to 9. - “a” characters : any numeric, alphabetic or special character of the centre four columns of the code table except position 5/15 and th
32、ose positions where there is provision for alternative graphic representation. tape mark : A delimiter used to indicate the boundary between file data and labels, and also between certain labels. In the basic system it is used to separate files. NOTES 1 The tape mark configuration is specified in th
33、e relevant Inter- national Standard for data interchange on magnetic tape cassettes 2 Throughout this International Standard the tape mark is in- dicated as an asterisk(). double tape mark : A delimiter consisting of two conse- cutive tape marks that is used to indicate the end of a volume or of a f
34、ile set. NOTE - Except in the basic system, two consecutive tape marks also occur when an empty file section or an empty file exists on a volume, in which case they are not interpreted as a double mark but rather as two single tape marks framing an empty file section. In this context “empty” means t
35、hat no blocks are present between the tape mark following the header label and the tape mark preceding the end of volume, end of track or end of file label of that file section or file 7 AMERICAN NATIONAL STANDARD ANSI/IS0 4341-1978 4 BASIC SYSTEM There are then two possibilities : 4.1 Introduction
36、4.4.1 If the file is not the last file of the set, the resulting configuration will be as illustrated in figure 2a). The basic system permits the structuring of one or more files on one volume by means of hardware separators (tape marks) only. Each volume is independent; multi- volume files are not
37、provided. No magnetically recorded labels are used. 4.4.2 If the file is the last file of the set, the next track will be terminated by a third tape mark as illustrated in figure 2b), in this case the last two tape marks are to be interpreted as an end of data indicator. The procedures for recording
38、 and detecting end of data on a track are defined in the relevant International Standards for media. a) Single file, one track 4.2 Use of tape marks Tape marks are used with the following significance to in- dicate the structure of volumes and files. b) Single file, two tracks 1 *FILEA* - Start of v
39、olume l . . . - File separator * . . . 1 l FILE A l 1 c) Multi-file, one track 1 l FILE A l FILE B * - intermediate end of track l . . . - Intermediate start of track * . . . d) Multi-file, two trades l FILE A l FILE B l - End of data (and end of volume) l * . . . It is not permitted for one file se
40、parator to be immediately followed by another since this signifies end of data; thus, there can be no empty file sections as described in the definition of “double tape mark” in clause 3. FIGURE 1 - File structure Two tape marks not signifying end of data may occur when an intermediate start of trac
41、k is immediately followed by a file separator : this condition is explained in 4.4 and 4.5. a) Intermediate start of trade followed by file separator Multi-file, two tracks, coincident end of file and intermediate start of track 4.3 Structuring the files pYEqA1 b) Coincidence of end of last file and
42、 intermediate start of trade Figure 1 illustrates the use of tape marks to establish the file structure according to the definitions of 4.2. In this figure and figure 2, the beginning of the tape is at the left and the end of the track is at the right. Each box represents a track. l FILE A l FILE B
43、l l * ICI l FIGURE 2 - File structure -Special cases If the end-of-tape marker is encountered whilst a data block is being written, then, unless the system avoids the situation by, for example, erasing the current block, the system will complete writing the data block, and will then close the track
44、with an intermediate end of track tape mark. The next track is opened with an intermediate start of track tape mark as illustrated in figure lb) and Id), and the file is continued. 4.5 Coincidence of end of file and intermediate end of track This situation arises when the end-of-tape marker is re- c
45、ognized whilst the system is writing the tape mark follow- ing a file. There are then two possibilities : 4.4 Coincidence of end of file and intermediate start of track This situation arises when the end-of-tape marker is recognized whilst the system is writing the last data block of the file. In th
46、is case the system will close the track and open the next track as indicated in 4.3, except that no data blocks of the completed file will be written in the next track, but only a file separator. 4.5.1 If the file is not the last file of a set, the track is terminated at that point, so that the tape
47、 mark already written is now to be interpreted as an intermediate end of track indicator. The next track starts with an inter- mediate start of track indicator, followed by a file separ- ator indicator, as illustrated in figure 2a). 4.5.2 If the file is the last file of a set, the system will write
48、a second tape mark to complete the track with an end of data indicator as illustrated in figures la) and lc). 8 l FILE B l FILE C l * 4.6 End of available space If the end-of-tape marker is recognized at the end of the last or only track on the volume which is available for recording, the file must
49、be terminated with an end of data indicator as illustrated in figure 1. 4.7 Recording density The blocks recorded on all volumes containing a file set shall be recorded with the same density. AMERICAN NATIONAL STANDARD ANSI/HO 4341-1978 4.8 By-pass or check-point records Only the relevant data blocks shall be written on a cassette used for interchange. Since by-pass information and check- point records are considered to be extraneous to the inter- change, and nostandard means of identification is provided, the recording of by-pass and check-point information is not allowed on cassett
