Namespace Registration for International Standard Serial Number (ISSN) and Linking ISSN (ISSN-L) based on ISO 3297:2007 Namespace ID: ISSN Requested of IANA. Version: 2 (revision of earlier registration, RFC 3044). Date: 2017-06-22 Registrant: Name: Gaëlle Béquet E-mail: gaelle.bequet&issn.org Affiliation: Director, The ISSN International Centre Address: ISSN International Centre 45 rue de Turbigo 75003 Paris France Web URL: http://www.issn.org Requesting entity is a standards development organization revising the namespace registration which was based on an earlier version of the ISSN standard. The formal URN Namespace Identifier Registration for the pre-2007 version of the International Standard Serial Number (ISSN) standard was done in RFC 3044 [RFC3044]. The revised ISSN standard does not require a new namespace, but the registration is updated here. The registrant organization has moved from a former address to a new one in Paris. Moreover, the description of the NSS and resolution details have been amended. Overview: Each ISSN is a unique identifier for a specific serial or other continuing resource in a defined medium. ISSN are applicable to serials and other continuing resources, whether past, present, or to be produced in the foreseeable future, whatever the medium of production. Continuing resources are issued over time with no predetermined conclusion, they include serials and ongoing integrating resources. ISSN are assigned to the entire population of serials and to ongoing integrating resources. Serials are resources for which additional information is supplied indefinitely in a succession of discrete parts. All serials are eligible for an ISSN. Also eligible for ISSN assignment are those bibliographic resources issued in successive issues or parts that bear numbering and that also bear other characteristics of a serial (e.g. frequency in the title), but whose duration is limited (e.g. the newsletter of an event). Ongoing integrating resources are resources that are updated over time and with no predetermined conclusion, for which the updates are integrated into the resources and do not remain discrete. This category includes loose-leaf publications, websites and databases. Those ongoing integrating resources that are eligible for an ISSN must be updated indefinitely, and/or have an update statement. Online ongoing integrating resources should meet some inclusion criteria in order to be eligible for ISSN assignment, for example an identified editorial responsibility and an editorial content (e.g. journalistic or scholarly content). Advertising and individual home pages, online diaries, personal weblogs, and web sites consisting exclusively of links are not eligible for an ISSN. Individual monographs, technical reports, sound and video recordings, printed music publications, audiovisual works and musical works have their own identifier systems. Such items may carry an ISSN in addition to their own standard numbers when they are part of a continuing resource, such as a monographic series. Only one ISSN is assigned to a continuing resource in a defined medium. This ISSN is permanently linked to the so called key title, a standardized form of title derived from information appearing on the continuing resource. A key title is unique to a particular continuing resource. Titles that would otherwise not be unique are made unique by the addition of qualifying elements. In cases where the title changes sufficiently (as per specific rules defined in the ISSN Manual) to warrant creating a new key title, a new ISSN is assigned. In cases where the medium of the continuing resource changes, a new ISSN and a new key title are assigned. Changes in publisher, country, language, frequency, subject scope or any other characteristic of a given continuing resource do not warrant the assignment of a new ISSN. Title changes that are deemed minor are registered in the ISSN metadata as "variant titles". When a new ISSN is assigned to a continuing resource (because of a significant title change or of a media change), both the "former" and "new" ISSN are deemed valid and identify two distinct entities: each of them identifies the continuing resource in its incarnation in a given time interval, under a particular key title and/or physical medium. Ceased continuing resources are no longer updated, but they continue to be accessible on library shelves or as archives on servers and their continuing identification is an obvious need for the whole chain of stakeholders. In such cases, ISSN, through the metadata stored in the ISSN records of the ISSN Register are reciprocally linked. In fact, one of the major aspects of the ISSN Register is its linking structure through which various incarnations of continuing resources are reciprocally linked using the ISSN as pointer. There are different categories of such links (for former and successor titles, other media editions, other language editions, supplements etc.). A given ISSN may thus be linked directly to a number of other ISSN, which in turn may be linked to other ISSN, etc. We can thus define the concepts of directly and indirectly linked ISSN. Purpose: ISSN is an authoritative standard identifier system for continuing resources and in particular serial publications. Therefore, any useful and deployable method for identifying these entities for network-wide reference and making their metadata available on the Internet needs to be based on ISSN. ISSN are authoritatively referenced in a centrally managed database called the "ISSN Register", which can be used as the basis for URN:ISSN resolution services. In the framework of URN:ISSN resolution, the ISSN-L is a very important feature. The ISSN-L (or "linking ISSN") is an important modification introduced in the 2007 revision of the ISSN standard within ISO framework. The ISSN-L has been defined to meet the need for a collocation, or grouping mechanism that brings together the various media versions of a continuing resource, and thus facilitate content management. The ISSN-L is an ISSN designated by the ISSN Network to group the different media versions of a continuing resource. Only one ISSN-L is designated regardless of how many different media versions of a continuing resource exist. A continuing resource will be associated with only one ISSN-L. The administration of the entire ISSN system is carried out at two levels: the ISSN International Centre and ISSN National Centres. The ISSN International Centre is located in Paris (France). The main responsibilities of this Centre are: • To promote, co-ordinate and supervise the world-wide use of the ISSN system. • To maintain and publish the ISSN Register. • To allocate blocks of ISSN to ISSN National Centres. • To assign ISSN to publications by international organisations and to serials issued in countries with no National Centre. Detailed information about ISSN usage can be found in the ISSN Manual which is available at: http://www.issn.org/understanding-the-issn/assignment-rules/issn-manual/ Syntax: An ISSN consists of eight digits. These are the Arabic numerals 0 to 9, except that an upper case X can sometimes occur in the final position as a check digit (when representing the number "10"). Since ISSN are likely to be used in the same context as codes designed for other purposes, a distinction must be preserved in the form of presentation. An ISSN therefore appears as two groups of four digits, separated by a hyphen: NNNN-NNNC where N is a Digit character [0..9] C is either a Digit character or letter "X" [0..9,X] C is the check character The check digit “X” must be upper-case. The hyphen is only used to increase the human readability of ISSN strings. This can be formally expressed as follows: issn-urn = "urn:ISSN:" 4DIGIT ["-"] 3DIGIT check check = DIGIT / "X" Example 1: ISSN 0317-8471 Example 2: ISSN 1050-124X The check digit is always located in the extreme right (low order) position, and is calculated on a modulus 11 basis using weights 8 to 2. The ISSN syntax (used literally as the NSS) is as follows: The URN syntax is urn::, where will be ISSN. The namespace, “ISSN”, is case-insensitive in processing but is conventionally written in upper case. Q-component semantics is for the time being undefined. F-component is not applicable, since ISSN does not identify journal issues or volumes, but the entire periodical. R-component semantics is for the time being undefined. Rules for Lexical Equivalence: The check digit, if 'X', is case-sensitive. Thus, if "x" is found it must be translated to “X”. The hyphen between the 4th and the 5th digit can be omitted Q- and R-components, if present, must be omitted Assignment: Assignment of ISSN is controlled, and 'ISSN' URNs inherit this property. There are three levels of control: the ISSN International Centre, national ISSN Centres, and finally all the stakeholders responsible for a correct use of the ISSN system. Assignment of ISSN-L is carried out either by a centre of the ISSN Network or is performed automatically as records are added to the ISSN Register. It is done either by those ISSN National Centres that are able to undertake this responsibility, or by the International Centre. The records produced by these National Centres include the ISSN-L in the ISSN records under their responsibility. The first ISSN assigned, in the ISSN Register, to any media version of a continuing resource is designated by default to function also as the ISSN-L and applies to all other media versions of that resource identified in the ISSN Register. An ISSN-L is designated for each continuing resource identified in the ISSN Register, even if the continuing resource is issued in only one medium. Only one ISSN-L is designated regardless of how many different media versions of a continuing resource exist. Security and Privacy: This document proposes means of encoding ISSN within the URN framework. An ISSN-based URN resolution service is depicted here, but in a generic level only; thus questions of secure or authenticated resolution mechanisms are excluded. It does not deal with means of validating the integrity or authenticating the source or provenance of URNs that contain ISSN. Issues regarding intellectual property rights associated with objects identified by the ISSN are also beyond the scope of this document. Access control mechanisms may be implemented to limit access to some or all URN resolution services available in the URN Register. Such mechanisms, if any, will be discussed separately. Interoperability: ISSN is a unique and persistent identifier. An ISSN, once it has been assigned, must never be re-used for another serial. Moreover, the same serial must never get a new ISSN. There are no characters in ISSN which would require percent-encoding. Resolution: For URN resolution purposes, all elements, including the check digit and the central hyphen, must be taken into account. If a local resource stores and manages ISSN without a central hyphen, it SHOULD be programmatically inserted for the constitution of URN:ISSN. Applications, such as the national bibliography or the open archive of a university, can use the URN as the persistent address of the resource. There is just one place (the URN registry) where the address is mapped to one or more physical locations. Persistence is one of the key features for any persistent identifier system. There are four inter-related aspects of persistence that need to be discussed: persistence of the resource itself, persistence of the ISSN, persistence of the URN-based resolvers and persistence of the ISSN-L. Persistence of the resources: Continuing resources are complex objects that evolve over time. In their paper incarnations, they have been stored on library shelves sometimes for centuries. Bibliographic records mediate identification and access. If a continuing resource is available on print only, its URN:ISSN will resolve to the bibliographic record in the ISSN register. The ISSN Register has identified (at the beginning of 2017) more than 200,000 online continuing resources that may or may not have print equivalents. Furthermore, vast digitization efforts are now undertaken over the world to create digital archives of printed continuing resources (these initiatives have often a dual aim of long term preservation and economies in shelving space); efforts are also under way to manage the long term preservation of online continuing resources. All these efforts that have as a goal the persistence of the continuing resources will be all the more successful if they benefit from a standardized identification layer. This obviously also has an impact on the management of contents (volumes, issues, and first and foremost articles) where linking frameworks that appeared during the last ten years (DOI or Open URL) make heavy use of the ISSN. Persistence of the identifier: The ISSN as an identifier is persistent in the sense that once assigned, an ISSN will never be re-assigned to a different continuing resource. Persistence of the resolvers: URN resolvers are not static. The services they'll supply will change over time, due to changes in technical infrastructure. For instance, new URN resolution services may be added or modified over time. Persistence of the resolvers themselves is mainly an organizational issue, related to the persistence of organizations maintaining them. As URN:ISSN resolution services will be based on the ISSN Register, which is itself a persistent resource that has been maintained for more than 40 years, we may thus assume that URN:ISSN resolution services will be persistent. The ISSN Register will initially support four resolution services specified in RFC 2483 [RFC2483], namely I2L, I2Ls, I2C and I2Cs. Only I2C and I2Cs (URI to URC(s); delivery of descriptive metadata related to the resource) are valid for non-networked resources. Descriptive metadata can only be supplied in the MARC21 format. Since the ISSN is not semantic, it is assumed that URN:ISSN resolution can only be reliably achieved through a central service, based on the ISSN Register that in turn can benefit from automated linking with other local resources using the ISSN as an identifier. Only a combination of the authority of the centralized ISSN Register and of local data can guarantee both reliability and persistence. ISSN-L In the framework of URN:ISSN resolution, whether an ISSN is submitted as an ISSN-L or as an ISSN should be considered as having no practical impact as the response should always include by default basic resolution data for all ISSN that may be linked through a common ISSN-L. For efficient practical resolution purposes, it should not be assumed that the requesting service has an unambiguous knowledge of either: • the media version associated to a given ISSN; or • the ISSN which is designated to function as the ISSN-L that links the different media versions. The URN:ISSN resolution service should make no such assumption concerning the knowledge of the requesting service. The URN:ISSN resolution should make available sufficient authoritative metadata so as to allow the requesting service to obtain the expected response, even if the ISSN submitted is not used fully adequately by the requestor. URN:ISSN resolution metadata should allow the requesting service to check and correct if necessary its potentially incorrect assumptions, so as to avoid the following situations: • an ISSN would be left unresolved (for instance because a "print" ISSN was sent instead of the "online" ISSN and I2L service is requested); • the requesting service would be left unaware of the existence of other ISSN linked through a common linking ISSN-L, because it would have submitted for resolution an ISSN not designated as ISSN-L; • the requesting service would have to perform several successive URN:ISSN resolution requests for all ISSN linked through a common ISSN-L. Examples (fictitious): URN:ISSN:1234-1231 identifies the current print edition of "Medical News". URN:ISSN:1560-1560 identifies the current online edition of "Medical News". The ISSN-L linking both media versions of "Medical News" happens to be ISSN-L 1234-1231 (i.e based on the ISSN 1234-1231, designated as such in the framework of the management of the ISSN Register). The resolution of URN:ISSN:1234-1231 should be equivalent to the resolution of URN:ISSN:1560-1560; i.e., in both cases one should find a reference to the other media version. Documentation: ISSN Manual http://www.issn.org/understanding-the-issn/assignment-rules/issn-manual/ Additional Information: See: http://www.issn.org Revision Information: This registration is based on ISSN standard version ISO 3297:2007. References Rozenfeld, S, Using the ISSN (International Standard Serial Number) as URN (Uniform Resource Name) within an ISSN-URN Namespace”, RFC 3044, January 2001