(' n.s: 15 41 A Reference Guide to the NTIS Bibliographic Data File An NTIS Data Base Reference U.S. DEPARTMENT OF COMMERCE National Technical Information Service 1978 Digitized by the Internet Archive in 2012 with funding from LYRASIS Members and Sloan Foundation http://archive.org/details/referenceguidetoOOunit A Reference Guide to the NTIS Bibliographic Data File An NTIS Data Base Reference Aid % f H U.S. DEPARTMENT OF COMMERCE National Technical Information Service 1978 Introduction This is the first edition of A Reference Guide to the NTIS Bibliographic Data File. It provides background material on the database which will be helpful to uses working with the NTIS files on their own computer service, on a publicly available on- line service, or in the printed format. This "Reference Guide" will eventually be a modular part of The NTIS Users Manual. Because it is the first module, it will be subject to revi- sion and improvement, as well as to the kinds of update which occur when dealing with a database whose file characteristics and content must change to keep pace with develop- ments in the report literature and information science and technology. Contents Page ABOUT NTIS 1 NTIS BIBLIOGRAPHIC DATA FILE 2 ELEMENTS OF NTIS BIBLIOGRAPHIC DATA FILE 5 ON-LINE SEARCHING HINTS 9 APPENDIX A: Lockheed Dialog Citation 11 APPENDIX B: SDC Orbit Citation 12 APPENDIX C: BRS Citation 12 APPENDIX D: GRA&I Citation 13 APPENDIX E: WGA Citation 13 APPENDIX F: DOE Accession Number Prefix Codes 14 APPENDIX G: Thesauri Used in NTIS Data Base . . 14 APPENDIX H: COSATI Subject Categories 16 APPENDIX I: NTIS Subject Categories 18 INDEX 22 About NTIS The National Technical Information Service (NTIS) is an organizational entity of the U.S. Department of Com- merce. Through special agreements with Federal agencies and Special Technology Groups, NTIS now serves as the primary source for the public sale of Government-sponsored re- search, development, engineering re- ports, and machine processable data files and related software. NTIS is obligated by Title 15 of the US Code 1151-1157 to recover its cost from sales and distribution of information products and services. The statutory mission states that NTIS will collect and sell copies of specialized technical information produced by Federal, State, local, and private sources, both foreign and domestic. (This includes data files and computer programs from Federal sources and U.S. Government-owned patent appli- cations). This is accomplished by promot- ing the use of these products by pub- lishing news bulletins and catalogs, by exhibits and speeches, by mail promo- tion and by other public and private mechanisms, such as marketing agents. About 70,000 new reports are added annually to the NTIS informa- tion collection of over 1,000,000 titles, of which 680,000 are computer re- trievable. The reports in the collection cover a full range of subjects includ- ing scientific, social, and economic research as well as documents and magnetic tapes containing business, management, transportation, and State and local government information. This input permits NTIS to serve a broad yet targeted group of users. NTIS customers, which total over 130,000, are worldwide. They include small businesses large corporations. Federal, State and local governments, special libraries, individual researchers and scientists, and the general public. The data base provides a means for this user community to keep up with the latest releases of information, or to conduct comprehensive reviews on topics of interest to them. The basic NTIS product is re- search reports. These reports are re- produced in paper copy and on micro- fiche. Some reports are available in other forms, such as magnetic tape, punched cards, or 16mm microfilm (reel or cartridge). All accessioned re- ports are permanently available. Several current-awareness prod- ucts are available to help users keep up-to-date on these research reports. The first product is the Government Reports Announcements & Index (GRA&I). It is an all-inclusive bi- weekly journal containing current technical summaries of all new publi- cations. Each issue contains about 2500 new entries. It is published for librarians, technical information spe- cialists, and those requiring all the latest summaries in a single volume with an index. For those with more precise interests and timely needs, NTIS provides 26 weekly abstract newsletters. These newsletters, which are indexed annually, are intended to meet the more individual needs of problem solvers and policy makers. For instance, one of the 26 news- letters, Government Inventions for Licensing, provides a central an- nouncement of new Government- owned patents and technology. Like the comprehensive journal, GRA&I, the newsletters contain brief descrip- tions of the latest publications avail- able. An important standing order service is Selected Research in Micro- fiche (SRIM). This product enables consumers to receive automatically, every two weeks, full-text copies (not just abstracts) of publications in spe- cific areas of interest, as they are ac- cessioned by NTIS. The reports, in compact microfiche forms, are dis- seminated at the rate of 2.000,000 copies annually. Customers can specify their interests by broad subject cate- gories or narrow subject index terms. Telephone discussions with NTIS analysts help decide which program is best. For customers who are interested in finding out what research has been completed before a certain date, NTIS produces on a regular basis cumula- tions of technical summaries in sub- ject areas of expected interest. NTIS has produced over 1000 bibliograph- ies. These tailored compilations, called Published NTISearches, provide fast, low-cost information on special inter- est subject areas. If more specific information is needed, immediate on-line access to the master file is also available. A tele- phone call to an NTIS analyst can establish what is available to match customer needs. A customized NTI- Search of the file can then be con- ducted. NTIS provides customers with leads to information, or copies of spe- cific publications. NTIS also has the capability to switch customers to spe- cialists. If information is needed on a very specific subject and documen- tation available from NTIS is not sufficient, NTIS will put you in touch with the specialists at one of the many Special Technology Groups. The work of these groups is highly specialized and covers a wide range of topics, such as plastics, cryogenics, nuclear rafety, engineering design, toxicology, metals and ceramics, and heat pipe technology. NTIS markets and dis- tributes the products and services of over 20 of these specialized informa- tion analysis centers. Another NTIS product and serv- ice is NTIS Tech Notes. This new concept in packaging provides custom- ers with easily readable selections of the latest on Federal technological ad- vances and inventions. Contributors to the series include: NASA, Bureau of Mines, Forest Service, National In- stitutes of Health, as well as the De- partments of Air Force, Army, and Navy. The Tech Notes are available in 1 1 different subject categories. The individual Tech Notes in each series include drawings, functional charts, formulas, and information on how to obtain complete backup information. Finally, NTIS has available data relating to demographic and geo- graphic situations. Through an agree- ment negotiated with the Lawrence Berkeley Laboratory, University of California, NTIS now provides cus- tom access to an enormous data base of 1970 Census data maintained by the Laboratory. The data base con- tains all of the employment-related information of the 1970 Census. Users needing data regarding utilization and availability of the labor force and users developing or measuring affirmative action plans have found this special service of great value. Some requests have been for national data while others have been for specific data for towns with a population of less than 2.500. NTIS analysts will help cus- tomers retrieve required information from the data available. Other data is also obtainable from NTIS in the form of data files on magnetic tape. Currently, over 1200 files are accessable. Simply contact the Computer Products Branch for more information. Additional services, such as the coordination, packaging, and market- ing of specialty publications for indi- viduals and organizations, may be specially designed to keep a specific user community up-to-date. 1 NTIS Bibliographic Data File DOE 92,000 NASA 96,000 Microfiche NTIS 640,000 CITATIONS Mag Tape 261,000 DOD 172,000 OTHER AGENCY Printed Copy (PB, Com, HRP, TT, etc.) Figure 1. NTIS BIBLIOGRAPHIC DATA FILE (1964-Present) For simplification, the NTIS Biblio- graphic Data File may be divided into four subsets. The file, which is avail- able for lease, contains reports from: (1) U.S. Department of Energy (DOE —formerly AEC/ERDA); (2) Depart- ment of Defense (DOD); (3) National Aeronautics and Space Administration (NASA); and (4) Other Agency. Figure 1 indicates the number of documents in the total NTIS collec- tion as well as the total for the various sub-sets for the years 1964 to the present. Ten years ago the information in our file and the requests for that information mainly focused on the physical sciences — physics, computers, chemistry, and geology. Today, due to the increasingly varied missions of Federal agencies, the NTIS file com- prises many reports, computer files, and programs on nearly every topic of practical importance. Figure 2 shows how the acquisition pattern has changed over the past 10 years. Table 1 emphasizes this changing pattern in the activity in the social science areas. Acquisitioned documents are "in- put processed," which includes De- scriptive cataloging, subject classifica- tion and indexing, and if necessary, abstracting. (See Figure 3.) Magnetic tapes received from DOE, NASA, DOD, Health Resources Planning GOVERNMENT ORGANIZATION REPORTS REGISTERED Department of Health, Education and Welfare 5200 Department of Commerce 2600 Environmental Protection Agency 1900 Department of Transportation 1500 National Science Foundation 1300 Department of Interior 1000 Department of Housing and Urban Development 400 Federal Energy Administration 200 Department of Labor 150 Department of Agriculture 100 Others 5800 Table 1. OTHER AGENCY (HRP), and SHARE (SHR) have been cataloged and indexed by subject spe- cialists at the respective organizations using their controlled language thes- auri. NTIS subject specialists will en- rich these data by assigning NTIS and COSATI subject category codes and other indexing terms. For Other Agency acquisitions, NTIS informa- tion specialists perform descriptive cataloging functions and subject analy- sis. Indexing terms are assigned using the Thesaurus of Engineering and Scientific Terms (TEST). This part of the accessioned workload goes through a minicomputer system. Tapes previ- ously received (NASA, DOE, DOD, HRP, SHR) are converted to the NTIS format using the NTIS IBM 360/40 and enriched. A clean merged tape of all segments of the file is then gen- erated from the 360/40. The master tape is then used for the Linotron photocomposition of NTIS journals and newsletters. Copies of the tape are leased for use in information process- ing systems and selective dissemina- tion of information. Data elements such as accession numbers, title, author, price, pagina- tion, descriptors, identifiers and ab- stracts, are now in machinable form and can be used to create document records or report summaries for the file. These elements are described in detail in the following pages. 1967 1977 OTHER AGENCY NASA 23% AEC 5% DOD 63% 27,500 REPORTS 58,800 REPORTS Figure 2. NTIS ACQUISITION Reformat for IBM 360/40 i Cataloging Subject Indexing Abstracting Key to Disk Photo- Composi- tion GRA&I, etc. I I I IBM 360/40 Master File Lease Files Figure 3. NTIS INPUT PROCESSING Elements of the NTIS Bibliographic Data File These file elements are arranged according to their field assignments in the NTIS bibliographical tape. Output formats will vary for different publications or on-line sys- tems. Sample output formats are shown in the appendixes A, B, C, D, and E. Document Accession Number — Field 01 Each report has a prime document accession number assigned in this field. This number should be used when ordering the report from NTIS. NTIS document accession numbers all have alpha prefixes. Certain prefixes are used exclusively for report collections input from specific agen- cies. The following list indicates commonly used NTIS accession number prefixes and the source agency for which they are used: Accession Number Prefix Report collection AD Reports received from the Department of Defense (DOD). Used from January 1964- present N Reports received from the National Aero- nautics and Space Administration (NASA). Used from January 1964-present PB Reports indexed, cataloged, and abstracted by NTIS for other agencies. Used from January 1964-present COM Reports received from the Department of Commerce. After 1974, PB accession num- bers were used for these reports. Used from January 1971-1974 E NASA reports dealing with research on LANDSAT imagery. Used from August 1972-present ED Federally sponsored reports announced for the Educational Resources Information Cen- ter (ERIC). Used from January 1972-present ESDU Reports announced for the Engineering Sci- ences Data Unit of Great Britain. Used from January 1975-present HRP Reports received from the National Health Planning Information Center under the auspices of the Bureau of Health Planning and Resources Development. Used from January 1976-present EIS Environmental impact statements received from the Council for Environmental Qual- ity. Used from June 1972 through April 1974 NTIS Reports prepared by NTIS. Used from No- vember 1972-present NTISUB Subscription items available from NTIS. Used from 1976-present JPRS Translations received from the Joint Publi- cations Research Services. JPRS translates for Federal agencies foreign language poli- tical and technical media primarily from the USSR and Eastern European Countries. Used from 1964-present PAT U.S. Government-owned patents or patent PAT-APPL applications. This is the official patent num- ber or patent application number issued by the U.S. Patent and Trademark Office. Patents and patent applications input by DOD and NASA do not have this report number prefix in this field. They use the AD and N prefix respectively. For DOD and NASA patents, NTIS field 14, report number, contains the patent or patent appli- cation number SHR Reports received from the Office of Inter- governmental Systems of the Department of Health, Education, and Welfare for their Project SHARE. Used from April 1977- present TT Translations prepared by the Special For- eign Currency Science Information Pro- gram (SFCSI) coordinated by the National Science Foundation. Used from 1964- present During the period 1964-1968, this TT pre- fix was also assigned to foreign translations indexed and cataloged by NTIS's predeces- sor, the Clearinghouse for Federal Scien- tific and Technical Information THE Reports received from the British Standards Institution for their Technical Help to Ex- porters service. Used from November 1975- present "Others" Most of the remaining prefixes are those used by the U.S. Department of Energy (DOE) and its predecessor organizations, the Atomic Energy Commission (AEC) and Energy Research and Development Admin- istration (ERDA), as well as reports from the International Nuclear Information Sys- tem (INIS) Most accession numbers listed in promotional pieces, current awareness media, and on-line systems will include an additional slash (at the end of the number) followed by up to four alpha numerics. If a numeric follows the slash it is a check digit. This check digit provides the NTIS request processing system with a means of checking to make sure customers do not miswrite any of the digits in the accession number when ordering a document. Following this check digit, there will usually appear two to three alpha characters called media codes. Media codes are used by NTIS to monitor its various products and services. We encourage customers to always include check digits and media codes when ordering documents so that we can provide better service and make products more useful. Sample accession numbers without check digits or media codes. AD-784731 AD-A007419 N76-10518 PB-253754 COM-75-50271 E75-10328 ED-126957 ESDU-76013 HRP-0010226 Format of accession numbers with check digits and/ or media codes. Media codes will be the same for a particular publication or product. NTIS/PS-76/0698 NTISUB/B/033-76-001 PATENT-3882208 PAT-APPL-633150 JPRS-54834 SHR-0200401 TT-75-59025 TT-75-59026/01 AD-784731/2GA AD-A007419/4GI N76-10518-85T PB-253754/ 6WC COM-75-50271/6 *E75-10328 *ED-126957 *ESDU-76013 HRP-0010226/9GI NTIS/PS-76/0698/ 1WG *NTISUB-B/033-76/001/ST *PATENT-3882208 *PAT-APPL-633150/GA * SHR-0200401 *TT-75-59025 *TT-75-59026/01 *ORNL-NSIC-114 *ERDA-TR-101 NTIS Subject Category Codes— Field 02 Two subject classification schemes have been used by the National Technical Information Service (NTIS) and its predecessor organization, the Clearinghouse for Federal Scientific and Technical Information (CFSTI). The schemes are the COSATI Subject Classification and the NTIS Sub- ject Classification. The subject classification schemes have three uses: (1) To sort by subject matter, the reports announced in the NTIS biweekly journal. Government Reports An- nouncements and Index (GRA&I), and the weekly abstract newsletters. (2) To selectively disseminate technical reports by NTIS using Selected Research in Microfiche (SRIM). SRIM provides customers with automatic distribution of full texts of reports in microfiche based upon the subject areas covered by these subject classifications. (3) To perform on-line searching of the NTIS data base. Subject classifications can be a useful tool for limit- ing an on-line search to a desired topic or for quickly selecting everything available in a broad area of interest. The COSA Tl Subject Classification Scheme This is an academically oriented subject classifica- tion scheme which has been endorsed by the Committee on Scientific and Technical Information (COSATI) of the Federal Council for Science and Technology. It is a uniform subject arrangement for the announcement and distribution of scientific and technical reports. The list is in two-levels consisting of 22 major subject fields (categories) subdivided into 178 groups (subcategories). The COSATI scheme has been in use since 1964 and has not been changed. This scheme is used to arrange reports in the biweekly journal, Government Reports Announcements and Index and also in its predecessor "This series does not have check digits and may or i not have media codes. journal, U.S. Governments Research and Development Reports. A list of categories and subcategories is listed in Appendix H. Complete scope notes for the COSATI subject cate- gories may be purchased from NTIS using the order number AD-6 12200. The price code for this report is A04 for paper copy and A01 for microfiche. NTIS Subject Classification Schemes In 1970 NTIS reviewed its procedures for subject classification. A new subject scheme was developed which could be used in conjunction with the COSATI Subject Classifications. The scheme, called NTIS Sub- ject Classification, provides useful sorting categories for both hard and soft sciences, particularly in areas such as environment, transportation, health, urban technol- ogy, etc. The scheme was further expanded in 1972, 1973, 1974, 1976 and 1977. Currently there are 39 major categories which are further divided into 325 subcategories. Twenty-six of these categories are used to sort reports in NTIS's weekly abstract newsletters. A list of all NTIS subject classifications is included in Appendix I. Complete scope notes and category listing for the NTIS categories may be purchased from NTIS by using the order number, PB-270575. The price code for this report is A05 for paper copy and A01 for microfiche. All of the subject categories consist of three-character codes; two numerics and one alpha character. The numeri- cal codes represent entire categories such as "chemistry" and "biology." The alpha codes are used to designate sub- categories within these broad categories. The COSATI subject categories range from 01 through 22. All reports are assigned at least one COSATI code. The NTIS sub- ject classifications range from category number 43 to category 99. Some NTIS subcategories may include an asterisk as a fourth character. The asterisk is used when NTIS selects a particular document as "better than aver- age", and uses the asterisk as a flag to sort and highlight these items in its abstract newsletters. NTIS Prices— Field 04 Listed in this element of the file are either the prices NTIS charges for reports or a variety of price text mes- sages. Paper copy report prices will be preceded by "PC" or "HC" (old format); microform (almost always micro- fiche) report prices will be preceded by "MF"; magnetic tape prices will be preceded by the words "Mag Tape". When the text messages "Not available NTIS" and "Re- print" appear, an availability statement will most often appear in the Availability Statement field (Field 22). Paper copy prices charged by NTIS are usually based on the number of pages in a report. Microfiche prices are usually a set amount no matter how many pages are contained in the report. Beginning in 1977 a price code, such as "A01", in- stead of dollar price has been used to indicate a report's cost. NTIS and data base vendors are in the process of converting all prices to price codes. Please write to NTIS for a current price code conversion table. North American Continent customers should ask for NTIS-PR-360-3; All others should ask for NTIS-PR-360-4. Corporate Source — Field 05 Listed here is the organization(s) that performed the research and prepared the research report. Since late 1974, the sponsoring organization(s) have also been included. Each corporate source is separated by at least one asterisk: beginning late 1976, all sponsoring organizations are pre- ceded by one asterisk (unless listed first) and cooperating performing organizations are preceded by two asterisks. The corporate source entry in NTIS citations is gov- erned by rules given in the following: Standard for Descriptive Cataloging of Government Scientific and Technical Reports. Available from NTIS as: AD-641092 Cost: Price codes— paper copy A04 microfiche A01 Other corporate cataloging guides include: COSATI Corporate Author Headings Available from NTIS as: PB-198275 Cost: Price codes — paper copy A99 microfiche — not available Title— Field 06 This field contains the report title which is entered using the cataloging rules given by the guides listed under "Corporate Source". For foreign language reports, the foreign title appears first with the English title in paren- ' theses. Journal and Data Base Issue — Field 08 This field contains a report's original announcement journal, volume, and issue in the format "JVVII": where "J" = a letter designating the journal; where "VV" = a two-digit volume number; and where "II" = a two-digit issue number. Some examples would be: U7404, N3310, and S0309. An exception to the above is found with DOE reports announced after the latter part of 1976. From that time on, DOE reports are given the NTIS U code. Reference is made to the DOE volume number at the end of each DOE abstract. The list below gives the meaning of the letters used in prefixing journal volumes and issues. Original Prefix Announcement code Journal Notes Used to identify reports for the Agency of International Development during August 1973. Used to distinguish reports input into the NTIS data base and not announced in Government Reports Announce- ments and Index or abstract news- letters. (Used after August 1976). Used to identify reports for the En- vironmental Protection Agency during July 1973. NSA Used to identify reports which were or announced in the journals Nuclear ERA Science Abstracts from volume 20, issue 12 (1964) through volume 33, issue 12(1976), and Energy Research Abstracts from Volume 75, issue 1 through volume 75, issue 10 and vol- ume 1, issue 1 (beginning 1976) to the present. Beginning in August 1976, this prefix was no longer used. The GRA&I U code now appears and reference is made to the DOE citation number at the end of each abstract. NTIS also announces" reports from the International Nuclear Information System (INIS). These are foreign re- ports dealing with nuclear technology sent to NTIS by DOE. They are an- nounced in GRA&I and in the journal Atomindex. After August 1976, the Atomindex citation number is refer- enced at the end of each abstract. STAR Used to identify NASA reports an- nounced in the journal Scientific and Technical Aerospace Reports, volume 3, issue 1 (1965) to the present. TAB Used to identify a small number of reports announced in the Department of Defense journal. Technical Ab- stracts Bulletin. USGRDR Used to identify reports announced in and the journals U.S. Government Re- GRAI search and Development Reports vol- ume 39, issue 1 (1964) to volume 41, issue (1966), and volume 67, issue 1, to volume 71, issue 5, and Govern- ment Reports Announcements and Index volume 71, issue 6 to the pres- ent. Reports announced in NSA, ERA, or STAR are also announced in GRA&I and its predecessor, USGR DR. Title Note— Field 09 Generally contains information that describes the type of report (a patent, annual report, final report, or technical report). This field sometimes contains a subtitle. Personal Author — Field 10 The author name for each report is listed here in the format of last name followed by first name or initial. The first five authors are entered. NASA and DOE do not spell out the author's first name, but use only initials. NTIS and other sources that do their own cataloging try to spell out the author's full name. An example of an author's name listed in these two ways is as follows: O' Brien, J. J. O'Brien, James J. Report Date— Field 1 1 This field usually contains the date that a report was completed. However, sometimes (almost always on trans- lations and journal articles) this date corresponds to some other time, such as the date of translation, the date of issue or filing for a patent, or the date of publication in some other journal. Since NTIS announces reports when released by the source agency for public dissemination, occasionally, NTIS will announce a report a number of years after it was written. Pagination — Field 1 2 This entry indicates the total number of pages in a report (including introductory material and appendix) except for reports not available in paper copy, such as magnetic tapes or microfilm. NTIS paper copy prices are usually based on the total number of pages in a report. An asterisk appearing after the page count indicates that the report was determined by NTIS to be of higher interest. Report Number — Field 14 This field may be blank or may contain one or two report numbers assigned by the performing organizations. When the performing and sponsoring organization are the same, the sponsoring organization report number will ap- pear in this field but not in the monitor number field. Report numbers all have alpha prefixes followed by numerics. Some examples of report number formats in- clude the following: CEL-TR-815 SU-SEL-74-001 NSF-RA-N-74-232 NSF/RA/N-74-0178 Contract or Grant Numbers — Field 1 5 This field contains the contract or grant number as- signed to a report's research project whether Federal, corporate, or academic. The field may be blank or may contain up to two numbers. Some samples of contract/ grant number formats include: NSF-GK-42356 EPA-68-01 2933 N00014-76-C-0487 Project and Task Numbers — Field 16/17 These fields contain identifying information for spe- cific projects or tasks within a given contract or grant. Some sample project/ task number formats include: UCAL-WRC-W-428 OWRT-A-062-MASS Monitoring Agency Number — Field 18/19 These fields are combined to produce the report number(s) assigned by the sponsoring organization(s) un- less it also is the perforrming organization(s); in this case, any monitor numbers are placed in the Report Number field. Some examples of monitor numbers include: EPA-WQO- 13030 EPA/ 560/ 7—75/ 000-1 W76-03962 Supplementary Notes — Field 21 Presents ad hoc statements with the following types of information: source of a translation; source of a periodical citation; other related reports; language of a report if other than English; superseded reports. Availability Statement — Field 22 A statement of availability will appear whenever there are special ordering instructions. This usually occurs when the report is either a "reprint" or "not available from NTIS." Descriptors — Field 23 Descriptors are single or multiword terms assigned by NTIS or other document-contributing agencies using the various controlled vocabulary thesauri or word lists in- dicated in Appendix G. These terms are posted to permit computer or manual subject searching. At least 12 descrip- tors are normally assigned per report. Descriptors preceded by an asterisk are those terms determined to be of significant importance in describing the subject content of a report. These asterisked terms can be useful in limiting an on-line search to reports of primary importance. At least one major descriptor must be assigned to a document. Most reports will average three or four asterisked descriptors. The limit of the total num- ber of descriptors is approximately 35 with an average of 15. Reports indexed by NTIS are assigned descriptors for concepts covered in the document. However, in order to be of help in searching, some reports are also indexed at both a high and low generic level. Reports announced by NTIS but indexed by other agencies contain that agency's descriptors from its own thesauri. The three major agencies currently entering their own keywords are DOE, DOD, and NASA. However, NTIS does enrich their indexing when it is felt additional concepts need to be expressed. This is done by adding terms to the identifier field. Identifiers— Field 25 Identifiers are single or multiword terms used to express concepts for which there are no adequate descrip- tors. Often these terms are selected from a controlled- language thesaurus different from the one being used to select the descriptors. A complete list of the thesauri used is presented in Appendix G. Identifiers preceded by an asterisk are those terms of significant importance in describing the subject content of a report. Their use and selection is the same as aster- isked descriptors. Identifiers include the names of chemical compounds, city names, biological species, and computer program Abstract— Field 27 Abstracts in the NTIS data base are indicative or in- formative. The type of document determines the type of abstract. Informative abstracts identify the methods, re- sults, applications, and conclusions; indicative abstracts describe content or scope: i.e., a handbook of chemical formulas; chapter titles or table of contents of a text book; scope and the number of references in a bibliog- raphy. Abstracts in the NTIS collection are usually limited to 200 words. The file contains a mixture of author- and NTIS-written abstracts. Many of the "author" abstracts are modified by NTIS subject analysts to meet standards re- quired in the system. Most NTIS citations contain abstracts; however, there are two major exceptions: (1) NASA reports announced prior to January 1973 do not have abstracts; (2) no Atomic Energy Commission (AEC) reports announced before July 1975 have abstracts. From July 1975 to January 1976 some AEC/ERDA report citations have abstracts. Begin- ning with Volume 1, Issue 1 of Energy Research Abstracts, all DOE reports have some type of abstract. Title Annotation — Field 30 This field is used to enrich titles and to provide addi- tional information for NTIS printed indexes. Corporate Source Code — Field 35 These are codes assigned by certain agencies to iden- tify corporate authors. DOE reports contain seven-digit codes. DOD- and NTIS-processed reports have five-digit codes. Many reports do not have corporate source codes. On-Line Searching Hints Accession number searching As was pointed out in the description of the accession number field, NTIS accession numbers often are suffixed with a check digit and/ or media code. When you wish to select an NTIS accession number in on-line searching you have two options: (1) display a list of the neighboring ac- cession numbers to select the correct number with its check digit and media code, or (2) truncate the accession number after the last slash to bypass all check digits and media codes. Chemical nomenclature NTIS indexes for specific chemical compounds using an abbreviated form of the system used by the Chemical Abstracts Service. Chemical compounds are listed in the identifier field unless they appear as an authorized descrip- tor. NTIS always attempts to hierarchically cover specific compounds with their chemical classes. An example of this would be the use of the descriptor, Nitro compounds, when using the identifier, Methane/ nitro. Some examples of the format of chemical names include the following: Disulfide/ bis(dimethyl-thiocarbamoyl) Mercury/ methyl Uracil/ bromo-butyl-methyl Uranium selenides Computer Programs NTIS has attempted to allow for searching of reports which have computer programs in them by only using the keyword, Computer programs, when a program is actu- allly listed in the reports. NASA maintains the same phil- osophy. This is not the case for reports indexed by DOE or DOD. DOE uses the keywords, "Computer codes," to identify either a listing of a program or to alert the user to the fact that a program exists, but may or may not be in the report. DOD reports are indexed with the keywords, "Com- puter programs," but again there may or may not be a computer program listed within the report. For users trying to locate computer programs in machine-readable form, the combination of the keywords, "Software," "Computer programs," and "Magnetic tape," should be used. Corporate source searching There are two types of corporate sources found in the NTIS data base: The performing organization(s) and the spon:oring organization(s). Performing organization Almost all reports are catalogued by the organization that prepared the report. Sometimes there may be more than 1 organization. In searching corporate sources cau- tion must be taken to accommodate the cataloging differ- ences caused by multiple agency input. These differences generally occur in abbreviations and punctuation. An ex- ample is the various ways that the Massachusetts Institute of Technology has been catalogued: Massachusetts Inst of Tech Massachusetts Inst, of Tech. Mass Inst of Tech Massachusetts Inst, of Technology Sp