The Global Language of Business
The Global Language of Business
Books and periodicals
Identification of books
The international standard numbering of books was introduced in Bulgaria in 1991 and is the responsibility of the National ISBN Agency at the National Library “Saint Cyril and Methodius”. For the unique identification of each title or edition, the Agency assigns an ISBN number (International Standard Book Number). As a rule, each publication receives one ISBN. A new ISBN is given when the book is republished. Books coming out in additional circulation, i.e. reprint, do not receive a new ISBN. Books published by two or more publishers are assigned two or more ISBNs of the respective publishers. Different language versions of the same book are given as many ISBNs as the language in which they were published. Multivolume editions are assigned an ISBN for the multivolume edition as a whole and an ISBN for each volume. Books that appear in multiple formats or bindings are assigned a separate ISBN for the individual editions. A change in book price does not result in a new ISBN. If a book is published on different information carriers (book body, on CD-ROM, Internet, etc.), as many ISBNs are given as the number of information carriers on which the book is published. If a book is published with and without an appendix, the respective editions are given separate ISBNs.
SBN encoding
ISBN is a numeric code that consists of 10 Arabic digits, from 0 to 9, with the last one being a control and sometimes X. It is mandatory to write the initials ISBN to distinguish it from other numbers and codes.
When encoding an ISBN with a barcode, 978 is added to the left of the number (without the check digit).
An EAN-13 symbol is used to encode the identification number thus obtained. In case additional information needs to be encoded, ADD-ON symbols can be used.
International Standard Periodicals Number (ISSN)
The determination of the ISSN number (International Standard Serial Number) and the registration of periodicals that are published in Bulgaria is the responsibility of the National ISSN Agency at the National Library “Saint Cyril and Methodius”.

  1. ISSN is a numerical code for periodicals, which consists of eight Arabic digits, from 0 to 9, the last one being a control and sometimes X. It is mandatory to write the initials ISSN to distinguish it from other numbers and codes.
  2. The sole purpose of the ISSN is to identify the title of the periodical.
  3. ISSN has no internal semantic elements to specify language, country or publisher. ISSN is compatible with ISBN. An issue in a series can have an ISBN as a book in that series and at the same time a series ISSN.
  4. Periodicals that are published in several languages ​​must have a separate number for each issue.

Advantages of ISSN:

  1. ISSN makes it possible to unmistakably identify a periodical, regardless of the country and language of publication.
  2. It enables fast and efficient communication between publishers, libraries, distributors and booksellers.
  3. Participates in the formation of the barcode for marking periodicals for distribution purposes.

Global Trade Unit Number
Another option for identifying periodicals is the assignment of a Global Trade Unit Number GTIN, formed on the basis of a company prefix for marking trade units, issued by GS1 Bulgaria.
Generate a barcode symbol for marking periodicals
1. Encoding ISSN number:
When encoding the ISSN number in a machine-readable form (barcode) for the needs of automatic processing of the information, the EAN-13 symbol is used. The 8-digit structure of the ISSN number received from the National ISSN Agency must be transformed into a 13-digit structure that corresponds to the 13-digit structure of the Global Trade Unit Number GTIN-13. For this purpose, a GS1 periodical prefix 977 is added to the left of the ISSN number (without the check digit). Two edition variant digits are added to the resulting 10-digit combination. Next is the calculation of a check digit, which is different for different combinations. The check digit is calculated using the GTIN-13 algorithm.
Positions N11 and N12 are used to identify variants of the same title when, for example, a promotional issue is issued at a different price, or to indicate the different issues of a daily newspaper within a week. These two positions can be formed on the principle of the counter for the individual variants (eg starting with 00, 01, 02 …. up to 99).
2. GTIN Encoding
When a Global Trade Unit Number is used to identify periodicals, the GTIN coding rules apply.
3. Add-on symbols
In addition to the publication ID, some publishers require coding and additional information for internal processing needs (eg inventory tracking). This can be done with additional ADD-ON symbols to the EAN/UPC barcode symbols. Additional symbols encode 2 or 5 digits and are placed on the right side of the EAN/UPC barcode symbol, parallel to it and at the same height. They are not scanned at retail checkouts.
Regarding the information in the additional Add-on symbol, GS1 has the following recommendations:
     A. Add-on-2
Daily: Each issue of a publication that is published each day of the week can be considered as a separate commercial unit and has its own identification number encoded with an EAN/UPC symbol. As an addition, the corresponding calendar week can be indicated by the Add-On-2 symbol. The combination of the information from the two symbols allows individual identification of each issue of the publication within a year.

  • Weekly: the number of the calendar week (01 – 53) is coded using the Add-On;
  • Monthly edition: Add-On is used for the number of the corresponding month (01 – 12);
  • Quarterly: Add-On contains the number of the first month of the corresponding quarter (01 – 12);
  • Seasonal: in the Add-On in the 1st position = the last digit of the current year, in the 2nd position = 1 for spring, 2 for summer, 3 for autumn, 4 for winter;

Yearly: in 1st position = last digit of current year, in 2nd position = 5

     Б. Add-on-5
Additional information may be a serial number or date of issue to distinguish between reissued variants. The encoding scheme is determined by the publisher. It is not allowed to use both types of Add-On symbols at the same time.
     C. Quality of additional symbols
Regarding the quality of the symbols in periodicals, it is not allowed to reduce the height of the symbol (by cropping) when exposed on the periodical. In case the size is reduced or increased, the Add-on symbols must be the same magnification factor as the EAN/UPC symbols.