ISO
LCISO 20775 defines an XML schema for representing library holdings information in a standardized, interoperable format. The standard enables library systems, OpenURL resolvers, and interlibrary loan services to exchange structured data about the specific items a library holds, including location, volume enumeration, chronology, and availability status.
Background
The need for a standardized holdings schema arose from the increasing interconnection of library systems and discovery services. While MARC 21 includes a holdings format, its binary structure was not well suited for web-based services that required lightweight, XML-based data exchange. ISO 20775 was developed to address this gap, providing a standalone XML schema for communicating holdings information independently of any particular cataloging format. The standard was published in 2009, with the Library of Congress hosting the schema and supporting documentation.
Purpose & Scope
ISO 20775 is designed to express information about what a library holds and where it can be found. This includes:
| Information Type | Description |
|---|---|
| Institutional identification | The library or branch holding the item |
| Location | Shelving location, sublocation, and call number |
| Enumeration | Volume, issue, and part numbering |
| Chronology | Date coverage of holdings |
| Availability | Current circulation status and restrictions |
| Copy information | Details about specific copies, including condition notes |
The schema supports both summary holdings (what range of volumes a library owns) and detailed item-level information (the status of a specific copy).
Key Elements / Properties
The top-level structure of the ISO 20775 schema includes:
| Element | Description |
|---|---|
| holdingSimple | A container for individual copy-level information |
| holdingStructured | A container for structured enumeration and chronology data |
| institutionIdentifier | Identifies the holding institution |
| physicalLocation | The physical location of the item |
| shelvingLocation | Specific shelving area within a location |
| callNumber | The call number or classification number |
| copyInformation | Details about an individual copy |
| enumerationAndChronology | Structured volume/date information |
| availabilityStatus | Whether the item is currently available |
Serializations & Technical Formats
ISO 20775 is natively an XML schema. The XSD schema file is hosted by the Library of Congress at its standards website. The schema can be used within other XML frameworks and is designed to be embeddable within larger metadata records, such as those returned by SRU/SRW services.
Governance & Maintenance
ISO 20775 was published by the International Organization for Standardization under ISO Technical Committee 46 (Information and documentation). The Library of Congress hosts the schema and acts as a key maintenance partner. Updates to the standard follow the normal ISO revision process.
Notable Implementations
ISO 20775 is used in library discovery systems and link resolvers that need to communicate holdings data in real time. It is particularly relevant in consortial environments where multiple libraries share a discovery layer and need to present holdings from different systems in a uniform format. SRU/SRW servers may return holdings data structured according to ISO 20775.
Related Standards
- MARC 21 Holdings Format -- The MARC-based format for encoding holdings data, which ISO 20775 complements by providing an XML alternative.
- MODS -- The Metadata Object Description Schema, which focuses on bibliographic description rather than holdings but is often used alongside ISO 20775.
- METS -- The Metadata Encoding and Transmission Standard, which can wrap holdings metadata in its administrative metadata sections.