ISO 18626 Interlibrary Loan Transactions

ISO TC46/SC4/WG14 Interlibrary Loan Transactions



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Last update: 8 January 2018


News and information about implementation of the new standard for ILL:

- ISO 18626 Information and documentation - Interlibrary Loan Transactions



ISO 18626 Information and documentation - Interlibrary Loan Transactions will at first supplement and eventually succeed ISO 10160, ISO 10161-1 and ISO 10161-2. Unlike its predecessor, ISO 18626 is well suited to the modern, Web-based technological environment which is based on XML and Web services. Another important difference between the two standards is that while the old standard is based on a 1980s model of ILL transactions, its successor is based on and supports much simpler exchange of transactions.


The standard includes three simple messages: a request, a supplying library message and a requesting library message and confirmations messages for this. The protocol is stateless, which means that there will be no need to maintain the interconnected state tables in the client and server applications (and the connections to the state tables in applications behind them). It is expected that the new ILL protocol will be much easier to implement than the old one, while still retaining the essential functionality of its predecessor.


ISO 18626 is the first part of a more general strategic initiative to standardize resource sharing in ISO/TC46/SC4 Technical Interoperability.



Open Codes

The list of open codes is prescribed in the standard, but will be continuous extended.



The guidelines and use cases is prescribed in the standard, but will be continuous extended.



XML Schema

The actual XML schema for ISO 18626.











To purchase the standard:

Contact your national ISO member body or use

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ISO Members:







Convener Leif Andresen

ISO TC46/SC4/SC14 Interlibrary Loan Transactions


Editors of ISO 18626: Leif Andresen (The Royal Library, Denmark), Clare Mackeigan (OCLC Relais), and Ed Davidson (OCLC).


Members WG14


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Dec 18, 2017

ISO 18626:2017 is now available. The new version includes a new element that allows the initial request to be more specific than in the 2014 version of the standard.


Some use cases fulfilled by the new version are:

         Book club request: requesting several copies of the same title may be for a specific period

         Specific time period: a book is wanted for a specific period of time, e.g. for an exhibition

         Patron request: to transfer a request from a bibliographic search tool to an ILL system

         Transfer request: to transfer a request between ILL systems


The new element RequestSubType is repeatable, because a book club request both can be for a specific period and for more than one copy.


This new element supports several functions (code values):


BookingRequest: Request for a specific period. Used together with StartDate and if relevant an EndDate


MulipleItemRequest: Bundle up more than one request for the same bibliographic item


PatronRequest: Create a patron-initiated request from an OPAC or search portal to the patron's local ILL system


TransferRequest: Intermediary service: handover management of an ILL request from one ILL system to another


SupplyingLibrarysChoice: A service defined by a Supplying Library, which a Requesting Library can select, e.g. a specific kind urgent delivery for an increased fee.


Updated schema are available at


21 July 2016

On Aug 17, 2016 join us at OCLC to learn more about ISO 18626.


More details are available in the

ISO 18626 Newsletter #3




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