[Home] HLAS Online as a Source for OpenURLs

A Guide for Librarians and System Administrators

OpenURL: What is it and how does it work?
Linking between HLAS Online and your Link Resolver
HLAS Online OpenURL Structure
Additional Information on HLAS Online OpenURLs

OpenURL: What is it and how does it work?

OpenURLs link online bibliographic citations for resources to related web services (such as full text databases, web search engines, and library catalogs). OpenURLs transport metadata and/or unique identifiers for a resource, along with contextual information, using a standard syntax. Sources that are “openURL-aware” generate OpenURLs and send them to the link resolver specified in the URL. Link resolvers are configured by their hosting institution to display a set of web services available to the institution’s users. Through a process known as “context-sensitive linking,” the resolver matches metadata contained in OpenURLs to appropriate web services. Depending on the web services that the institution supports, the resolver may link a user directly to digital full content or provides them with a services menu containing links to OPACs, web search engines, tables of contents, abstracts, online bookstores, fee-based document delivery services, interlibrary loan applications, A-Z name/title lists, online reference, or other web services. The OpenURL framework has been defined as a NISO standard.

HLAS Online is an OpenURL-aware source. If your institution has a link resolver, you can configure your system to embed OpenURL links in HLAS Online search results. When OpenURL is enabled, HLAS Online full record displays will include links to the web services offered by your institution.

Linking between HLAS Online and your Link Resolver

To activate an OpenURL link between HLAS Online and your link resolver, the URL you use to connect to HLAS Online must identify the base URL (address) of your resolver and, optionally, the URL for the icon file to be used to activate the OpenURL link in the HLAS Online full record display.

Configure the URL you use to connect to HLAS Online as follows:

& OpenLink=<yoursite.org/linkicon.gif>
& Redirect=http://lcweb2.loc.gov/hlas/mdbquery.html

If no OpenLink icon file information is included in your URL, the term “Availability” will be used as the OpenURL link text in HLAS Online full record displays.

The URL you use to connect to HLAS Online sets a cookie in your user’s browser which expires when the browser is closed.

When your users click on your OpenURL link icon or the term “Availability” in the full display of an HLAS Online record, a new browser window will open with the OpenURL as the http address. The HLAS Online session will also remain open.

HLAS Online uses HTTP POST for all OpenURL transactions.

image of an HLAS record

HLAS Online OpenURL Structure

HLAS Online OpenURLs are currently constructed according to OpenURL version 0.1 specifications. These OpenURLs have three components: the base URL of your institution’s link resolver, an identifier for HLAS Online as the OpenURL source (“origin-description”), and citation metadata (“object-description”):

http://<yoursite.org/yourresolver>?sid=LC:HLAS&genre={genre}&[additional metatag/value pairs]


HLAS Online is identified as the source of the OpenURL through the identifier: “sid=LC:HLAS”


HLAS Online OpenURLs use the following metadata elements: genre, isbn, issn, title, volume, issue, pages, date, aulast, atitle. Metadata elements are separated by ampersands (“&”) and follow the syntax: metatag=value. Abbreviated journal titles found in HLAS Online MARC21 field 773 are replaced by fuller journal titles to improve query results. Metatag/value pairs appear only when information is available.

genre: HLAS Online OpenURLs are constructed for the OpenURL genres: article, bookitem, book. Genre is determined by data in field 773: 773$7 “nnas” maps to article; 773$7 “nnam” or “m2am” map to “bookitem”; and the absence of field 773 maps to “book.” Nonprint materials (sound recordings, electronic resources, etc.) are currently treated as “book.”
isbn: taken from 773$z if present, otherwise from 020$a; does not include hyphens
issn: taken from 773$x if present, otherwise from 022$a
title: taken from 773$t or 773$p (abbreviated serial titles found in 773$p are mapped to the fuller form of the title); otherwise from 245$a
volume: parsed from 773$g, if 773$7 data for article genre is present
issue: parsed from 773$g, if 773$7 data for article genre is present
pages: parsed from 773$g, if 773$7 data for article genre is present
date: parsed from 773$g, if 773$7 data for article genre is present
aulast: OpenURL version 0.1 does not distinguish between personal, corporate or conference names. Therefore, HLAS Online maps “aulast” to: the last name of first personal author taken from 100$a (up to but not including the first comma), or the name of corporate or conference authors taken from the 110$a or $111$a
atitle: taken from 245$a, if 773$7 data for article or bookitem genres are present

Diacritics are removed from metadata in the “title,” “atitle,” and “aulast” tags. Reserved characters are escape-encoded for appropriate URL transmission.

HLAS Online uses these metatag/value pairs in the “object-metadata-zone,” but does not use either the “global-identifier-zone” or the “local-identifier-zone.”

Additional Information on HLAS Online OpenURLs

HLAS Online includes citation records for volumes 1 (1936) to the present. OpenURL links are available for records from volume 50 (1990) forward, which are formatted using MARC21. At this time, citation records from volumes 1-49 do not contain sufficiently structured metadata to generate useful OpenURLs. Please send any questions about configuring OpenURL access for HLAS Online to: hlas@loc.gov.

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Comments: Ask a Librarian (03/26/09)