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The Library of Congress > Program for Cooperative Cataloging > CONSER > ISSN and Seriality by Regina R. Reynolds May 1998


What is a serial? Which publications--especially electronic ones--should be eligible for ISSN? What kind of records should the ISSN Network create for electronic serials? These and similar questions were addressed by the ISSN directors, following my presentation of a discussion paper, "Ongoing Publications and the Redefinition of "Serial,"at the 22nd Meeting of Directors of ISSN Centres held in Budapest in May 1997. Our discussion was largely theoretical. It was prompted both by changes in serials themselves and by the ideas in a paper, "Issues Related to Seriality,"(1) by Jean Hirons and Crystal Graham which was to be presented at the International Conference on the Principles and Future Development of AACR to be held in October 1997 in Toronto.

In the year that has passed since our discussions in Budapest the questions raised by electronic serials and by the AACR conference have become less a matter of theory and more a matter of future reality. The AACR Joint Steering Committee recommended that AACR rule revision proposals be prepared to implement the key concepts expressed in the Hirons/Graham paper: A serial should be defined by the continuing or "ongoing" nature of its content. Descriptive rules for serials should be compatible with the publication pattern or "form of issuance." We should catalog the whole serial and not concentrate on a single issue. The rule revisions are on a "fast track" and the goal is to have a package to JSC by the end of 1999.

Impact on ISSN Network

Thus, countries which follow AACR (and this includes more than the Anglo-American countries) will definitely see changes in serial cataloging and a probable broadening of publications which are treated like serials. And, because of the increasing internationalization of cataloging and the desire to use catalog records created in other countries, these changes in AACR are likely to have an impact even beyond those countries which now use AACR. Furthermore, ISBD(S) is currently being revised and it is likely the AACR changes will have an effect on this revision of ISBD(S). Since it is important for ISSN rules and ISBD(S) to be compatible, and since an increasing number of ISSN centers use one record for both ISSN and national bibliography records, changes in cataloging rules are bound to have a profound effect on the ISSN system. Furthermore, if the ISSN is to continue to be a viable identifier for the electronic age, then the ISSN Network must address many of the same questions about seriality that are being addressed in the AACR revision

Outline of this Paper

In this paper I want to first explore the background to the seriality problem: the characteristics of electronic serials that are causing present rules to be inadequate; as well as the current rules and practices, and where they are lacking with regard to electronic publications. I will then explain the proposed AACR solution, the concept of "Ongoing Entities" and describe Modified Model C, (2)(3) a model developed by Jean Hirons and myself which shows the sub-categories of Ongoing Entities and various types of publications which fall into each category. Next I will discuss ways of handling title changes on electronic serials, giving the pros and cons (as they affect cataloging records and ISSN records) of successive entry, latest entry and new approach called "incorporating entry" recently proposed by Sara Shatford Layne of UCLA (4). Finally, I will discuss some areas of serials description for which AACR proposals are also being considered.

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The Problem

Once upon a time, the bibliographic world was pretty much black and white: we had monographs and we had serials. There was not too large of a gray area in between except for loose-leaf publications. But, with the explosion in electronic publishing, many new forms have appeared and many old forms (such as journals) are behaving in new and different ways, to the point where Crystal Graham has jokingly characterized electronic serials as "serials on drugs." Besides their ability to incorporate sound, video, and hypertext links, another thing some of these publications do is to publish articles one at time, ignoring the need for issues. Even those journals that do preserve the arrangement into issues might not have the journal title anywhere on the individual issue, and might not have the journal title on the articles either. In some of these journals the only place the title (and often other publishing information) appears is on a Home Page which serves as the introductory page to all of the contents on the Web site. This presents a problem for description (no current or earliest issue to describe from) but an even greater problem when the title on the Home Page is replaced by a new title, leaving nothing online with the old title. The problems this causes will be discussed under the section called Handling Title Changes.

Another problem electronic publications present is that some publications, such as abstracting and indexing services or annual directories, have been cataloged as serials in print but when they are put online they take a database format with no visible parts--no issues or even volumes--and thus they become, at least by current definitions, monographs! This is a difficult transformation for even librarians to understand and has been causing problems from those who expect that a publication is either a serial or a monograph, but not both at once! And finally, the electronic age has brought us entirely new types of resources--one isn't even sure if they can be called publications. The group working on revising AACR definitions is using the term "entities." Web sites and discussion lists, for example, would seem to be ongoing but not necessarily serials. So... once again we are faced with the same questions, What is a serial? What should cataloging rules and the ISSN Network do about new forms of publication?


The current definition of "serial" in AACR is "A publication in any medium issued in successive parts bearing numerical or chronological designations and intended to be continued indefinitely." The ISDS Manual includes this definition: "A publication, in printed form or not, issued in successive parts usually having numerical or chronological designations and intended to be continued indefinitely." The AACR definition of monograph begins quite simply: "A non-serial item..."

As electronic publications have become more numerous so have the problems with the current definition become more obvious: some electronic serials are unnumbered, some are not issued "in successive parts," some have become online databases. Additionally, because currently a publication can be a serial in print but a monograph in its online form, records for the same publication in different media may reside in different files in a library which can interfere with effective storage, retrieval, and locating these related publications in online catalogs.

Proposed Solution: "Ongoing Entities"

The "ongoing" concept was first proposed in the 1997 Hirons/Graham paper, "Issues in Seriality." However, the model recommended for short-term implementation in that paper proved unworkable and a new model (Modified Model C) was developed by Jean Hirons and Regina Reynolds in April 1998 and presented in a paper, "Proposal to Adopt a Modified Model C" which can be found on the CONSER Web site. In this model the "bibliographic universe" is divided into "Monographic Entities" and "Ongoing Entities." Monographic Entities are complete as issued (whether in one or more parts), while Ongoing Entities are intended to continue for some time, though not necessarily indefinitely. "Ongoing Entities" is an "umbrella" category which is further divided into various sub-categories, among which are serials, series, and such new entities as databases and Web sites.

Just what does the creation of the "ongoing" umbrella accomplish? To begin with, it covers gaps in AACR by accommodating types of publications which are not covered at all, such as loose-leafs, databases and Web sites. Also, having this overall category keeps the manifestations of a work (in various media) together. It recognizes that the potential for change applies more broadly than the narrow category of serials and it provides (via its subcategories) the basis for determining the number of records to cover title changes. It provides overall common treatment for the ongoing nature of the publications it encompasses but also allows for some areas of differing treatment for the various types of ongoing publications. Finally, it recognizes seriality without making everything a serial! What the ongoing umbrella concept does not do, however, is to specify where in AACR2 rules for each category should be covered; WHO should catalog WHAT (monograph or serial catalogers, CONSER or ISSN programs); nor does it call for changes in everything serials groups do; there is still a category for serials as we now know them and it is expected that the treatment of traditional serials will remain pretty much the same as it is now.

The Model

Let us now take a closer look at the model and its categories. "Monographic Entities" includes books, electronic texts, and entities that are irregularly revised such as textbooks which are issued in infrequent editions. "Ongoing Entities" includes serials (as now defined), series (both numbered and unnumbered), multipart sets and collections that are not complete as first issued, loose-leafs, and electronic resources that are intended to be added to/updated for some time (e.g., databases, Web sites, etc.)

There are two main categories of Ongoing Entities: Successive Entities With Discrete Parts, and Integrating Entities. This primary division is made on the basis of what Hirons and Graham called "form of issuance," a term which refers to the presence or absence of discrete parts and the number of "chief sources" at any given time. Form of issuance was chosen as the basis for determining the two main categories rather than whether the publications was intended to continue indefinitely because form of issuance has a greater influence on description and for certain ongoing entities, such as loose-leafs and Web sites, it is very difficult to determine the intention to continue indefinitely.

Successive Entities With Discrete Parts are characterized by being issued in a succession of parts with multiple sources of title over time. They are further divided into those that are intended to continue indefinitely (serials, series) and those that have a preplanned end (sets, collections). By dividing successive entities in this way, we can take into account the nature of the work (planned as a whole or evolving), we can distinguish serials from multipart sets and we can also preserve a category for serials as we know them. Finally, the structure of the model permits more categories to be added as new types of entities arise.

Integrating Entities are characterized by having a single source of title than can change over time, and by having parts that are integrated seamlessly into an existing whole. For integrating entities, no attempt is made to determine whether they will continue indefinitely; it is sufficient to know they will continue over some period of time. This solves the problem of trying to make this difficult determination for Web sites, databases, or loose-leaf publications, all of which fall into this category. Like the other categories, it can be expanded to accommodate new types of entities.

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Electronic Journals

As I noted earlier, electronic journals present particular difficulties for cataloging because some of them have discarded traditional patterns of serial publishing such as publication in issues, and some have even discarded traditional elements found on serial publications, such as titles on issues, numbering, publishing statements, or frequency statements. Of course, we need to keep in mind that electronic publishing is still in its infancy; publishers are still learning what works in this new medium and still experimenting with different models. It may well happen that some patterns will emerge, into which most journals will fall, such as is the case with print publishing. However, in the meantime, those of us dealing with electronic journals are faced with some which are published in a way that is identical to a print journal with numbered issues, covers, etc., and others which look on the Web like one large database of articles. The former pattern would fall into the "Successive Entity" category while the latter pattern would fall into the "Integrating Entity" category. Some electronic journals fall somewhere in between. And, to add to the problem, some e-journals start out as successive entities but change their pattern to an integrating one, while others have changed in the opposite way. How, then, can we determine how to catalog them?

Handling Title Changes

Because publications such as loose-leaf services, and databases which are not successively issued, fall under the "Ongoing Entity umbrella" we now have to consider the question of how to handle title changes for publications such as these where the old title may completely disappear. Many librarians do not feel it is appropriate to have records in their catalogs for titles which no longer exist. (Unlike print serials where the old title still exists on the back issues, unless the electronic publications are archived under their old titles, once these titles are gone from the online version, the old titles may no longer appear anywhere.) In order to understand the questions involved in determining the best form of cataloging for these new types of publications, we need to review the traditional ways of handling title changes: successive entry and latest entry, as well as consider a third convention, "incorporating entry" recently proposed by Sara Shatford Layne in a paper entitled, "Incorporating Entry." Below is a table containing records created under these three types of approaches.


Records Created Under Three Approaches
Successive Entry Latest Entry Incorporating Entry
Journal of A 
ISSN 1234-567X
785 Continued by Journal of B
Journal of C  
ISSN 1543-4576
Title varies: Journal of A
ISSN 1234-567X, 1960-1970;
Journal of B, ISSN 1432-8765;
Journal of A  
ISSN 1234-567X
7?? Incorporated into Journal of B
Journal of B
ISSN 1432-8765
780 Continues Journal of A
785 Continued by Journal of C
Journal of B  
ISSN 1432-8765
7??Incorporates Journal of A
7??Incorporated into Journal of C
Journal of C
ISSN 1543-4576
780 Continues Journal of B
Journal of C  
ISSN 1543-4576
7?? Incorporates Journal of A
7?? Incorporates Journal of B

Latest and Successive Entry

Successive entry is the current practice used with AACR and ISSN rules. Under successive entry, a new record is created for every significant title change. Earlier and later titles are handled by linking fields. The start and end dates on a record refer to that particular title only. Under latest entry (a practice used in AACR until 1971 and no longer permitted and one never used in the ISSN Network) current and former titles are all included on one record. The current title is always in the "cataloging title" position (field 245) and when the 245 title changes, it is moved to a title varies note (field 247) and the new title takes its place in field 245. The start date on the record is the start date of the earliest title in the title varies note.

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Pros and Cons

Successive entry records are shorter and simpler than latest entry records. The one title/one record approach facilitates linking and adding holdings to records. Successive entry works well in cooperative databases and union listing situations because libraries can "claim" only those titles they actually hold. On the other hand, successive entry results in multiple records for what many perceive to be the same publication. When you look at the preceding table, latest entry looks like the simplest and most efficient approach: all information is on one record.

However, in addition to making cooperative databases and union lists difficult, there are other drawbacks to latest entry as well, especially for the ISSN Network. Latest entry records, especially for serials which have a long life, can become very long and complex. Also, sorting out which identifying information goes with which particular title on a latest entry record can be difficult. If the ISSN Network continues to assign a new ISSN each time the title changes, it will be difficult for centers which use the same record for ISSN and their national bibliography to create separate successive entry records for the ISSN database.

If, on the other hand, the ISSN Network were to keep the same ISSN for Integrating Entities even when the title changed, we would be faced with several even more difficult problems. To begin with, could publishers possibly understand our use of different title change rules for different serials? Just when we have at least some publishers able to understand that when they change their title they need to obtain a new ISSN, we would have to tell them that was not true in some cases. Also, if the key title no longer identified what an ISSN was assigned to, what would take its place? And, would a latest entry assignment policy be compatible with other systems which use the ISSN such as the SICI and the DOI? But most challenging of all would the problem of trying to determine, each time we received an ISSN request for one of these entities, if we had already assigned an ISSN to that publication under an earlier title, a title which could possibly be two or even three titles back. As we know, publishers sometimes do not know about earlier titles, especially if they have purchased the serial from another publisher. Of course, even now we do not always know about earlier titles but if we do not, the most serious problem is a missing link. If we were using latest entry, the consequence of not knowing an earlier title would often be a duplicate assignment of ISSN. Many such duplicate assignments might seriously threaten the integrity of the ISSN system. It is my understanding that it was this problem which made those designing the ISSN system realize that it had to be based on successive entry and I believe it was no coincidence that latest entry died at about the same time that cooperative online databases and the ISSN system were born.

Finally, I believe that mixing latest and successive entry records in one database would be extremely difficult and confusing. In database terms, some records would represent one object, other records would represent more than one object. It would be difficult for database users who were not serials librarians to even understand and interpret the mix of records. Start dates would mean one thing on latest entry records and another thing on successive records. If a title were published both in print and electronic form, the records would each be created according to different principles and would look very different. Linking between the different records would be a nightmare.

Incorporating Entry

Just when the drawbacks of successive, latest, and a mixture of records for describing some online serials seemed insoluble, a proposal for "Incorporating Entry" was made by Sara Shatford Layne at the May 1998 CONSER Operations Meeting. Under incorporating entry a new record is created for each title change, just as in successive entry. However, under this form of entry, each new record incorporates the title of the previous record. So, the start date of each record is the same as the start date of the first title in the chain of successive titles. Records contain links forward and backward that signify "Incorporates" or "Incorporated into" respectively. It has not been determined yet whether the most recent record in the chain would contain links for all incorporated titles. If this were to be the case (and I am inclined to support this) then an individual library could retain only the most recent record in its catalog, while national bibliographies, union lists--and perhaps the ISSN database--could retain all of the records. Thus, incorporating entry is somewhere in between latest and successive entry. Like successive, new records are created for each title change, but like latest, one record can represent the entire publication.

The incorporating entry approach is what a CONSER cataloger might do today if she needed to catalog a serial that changed title and was purchased by a new publisher who re-issued all the old issues from vol. 1, no. 1 to the present under the current title. To catalog this serial in the CONSER database the cataloger would create one new record with a coverage date which was the beginning date of the original serial and with a title access point for the earlier title that the new serial incorporated. I believe that incorporating entry--if it is further developed and agreed upon as part of the AACR revisions--is a concept that might help solve the problem of how to keep the ISSN system compatible with new cataloging approaches for electronic serials. If latest entry were used, as I have noted above, there would be serious problems for the ISSN. However, if the ISSN Network were able to adopt incorporating entry--or something like it--for at least some kinds of electronic serials, libraries that follow AACR might be able to continue to use the same record for both their national bibliography and their ISSN work.

Although we need to keep in mind that incorporating entry as well as other details of the AACR revisions are still being worked out, it is clear that AACR rules will definitely change and ISBD(S) will probably change in order to accommodate new forms of electronic publications. The ISSN Network needs to be prepared to respond to changes in forms of publication and cataloging rules as well.

Challenges for the ISSN Network

  1. To which types of electronic publications should ISSN be assigned? successive entities only (as now) all integrating entities (would include Web sites, databases) all "electronic journals" regardless of form of issuance (would include some in database format) some integrating entities only, e.g., databases, electronic journals, but not Web sites
  2. Can the ISSN Network afford to not include some types of electronic publications and still remain viable in the face of DOI, URN, etc.
  3. What will be the consequences if AACR and ISBD(S) change and ISSN rules do not?
  4. Since the from of issuance for electronic journals can be either Successive or Integrating, should the decision as to whether we assign ISSN to electronic journals or not, and how we handle the title changes for electronic journals, be determined by their form of issuance (keeping in mind that it can change) or should we arbitrarily decide on a single policy for all electronic journals?
  5. If ISSN are assigned to any Integrating Entities (databases, some electronic journals, Web sites) how will we handle title changes?
  • continue to assign new ISSN and create new successive entry records (as now)
  • continue to assign new ISSN but use latest entry records for Integrating Entities
  • continue to assign new ISSN but use incorporating entry records for Integrating Entities
  • do not assign new ISSN and use latest entry records
  • do not assign new ISSN and use incorporating entry records

Other Cataloging Problems

The Hirons/Graham paper raised a number of other cataloging problems for which groups working on the AACR proposals are also preparing recommendations. One issue with potential to affect the ISSN Network is an attempt to increase the number of minor title changes not requiring new records. Since such a change could cause some catalog records to get out of sync with ISSN records and rules, the AACR revision group hopes to develop this proposal in conjunction with the ISSN Network. If this joint effort were successful, the result would be an increase in the number of title changes which do not require new ISSN. An example of such a case is the addition or deletion of the word "magazine" or other generic words and their equivalent in other languages from a title. Another example is an attempt to devise some kind of "uniform title" for conference proceedings that was not as closely tied to the exact wording on the title page as is the key title or cataloging title under current rules.

Other AACR proposals will focus on the description of electronic serials and will address the sources of description for electronic serials, the need to record a "date viewed," and specify which other descriptive fields should be used.

One final area of interest to the ISSN Network is consideration of use of the key title as a general "uniform citation title" in catalog records. Currently under AACR, when serials entered under title do not have a unique title a "uniform title" is created following rules that closely match those for the key title. One possible outcome for this proposal would be the elimination of the uniform title and the use of the key title if one were available. If no key title were available, a provisional key title would be created according to the rules for constructing key titles. If an ISSN center later assigned a key title to that serial, if possible, the ISSN center would authenticate the provisional key title unless it were completely unusable, in which case the authenticated key title would replace the provisional key title.

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We in the ISSN Network have several extremely important and difficult challenges facing us. Even though the needs of the ISSN Network are unique in some ways, nonetheless we can find help in the work done for AACR and the work that will be done for ISBD(S). We can also contribute our assistance and insights to both of these groups. So, instead of being troubled by these challenges (something I have found easy to do!) we can, instead, look upon these challenges as evidence of the success of the ISSN. If ISSN were not in such widespread use around the world, we would not have these problems but neither would we have the satisfaction that will come with preparing the ISSN to be a successful identifier for serials well into the 21st century!


  1. Hirons, Jean and Crystal Graham, "Issues Related to Seriality" in The Principles and Future of AACR: Proceedings of the International Conference on the Principles and Future Development of AACR, Toronto, Ontario, Canada, October 23 - 25, 1997. Ottawa: Canadian Library Association; London: Library Association Publishing; Chicago: American Library Association, 1998.

    The CONSER Web site contains the following papers at which directly relate to the topics discussed in this paper:

  2. Modified Model C by Jean Hirons and Regina Reynolds
  3. Diagram of Modified Model C
  4. "Incorporating Entry" by Sara Shatford Layne


1. An alternative to Incorporating Entry, the creation of a succession of Latest Entry records, has been proposed in November 1998. This proposal can also be found on the CONSER Web site.

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