[UPDATE: This meeting IS happening and is now scheduled for Tuesday, April 5 from 9-10am in Wells Library 043. Apologies for missing the meeting where this was originally scheduled but this thing is BACK ON! And don’t forget to check out Jennifer’s post discussing More about MODS (and XML) to learn more about MODS and its uses before we meet.]
It’s been a while since the Metadata Discussion Group last met but Jennifer and I think we have something that could benefit from a few more metadata-aware eyes at IU. If that’s you, or if you’re interested in topics like transforming metadata or linked library data, read on!
There is an ongoing effort in the Hydra community to figure out strategies to deal with descriptive metadata in RDF for use in Fedora 4 (the digital object repository that we hope to upgrade to here at IUB Libraries). The MODS and RDF Descriptive Metadata Subgroup, lead by Steven Anderson from the Boston Public Library, is working on how to handle MODS XML as RDF that will create a usable, if unofficial, metadata application profile to bring MODS into Fedora 4 as RDF properties.
So far this work has involved going through MODS element by element using examples from various institutions and asking the question “If [you] had to move that [MODS element] to RDF in Fedora 4 today, what would [you] chose to do with it?” (see the work for Abstract as an example). The MODS elements examined so far include name, title, typeOfResource, genre, originInfo, physicalDescription, abstract, language, and current work is happening on tableOfContents.
Join us on Tuesday, April 5 from 9-10am in Wells Library 043 to learn about this effort and Indiana University Libraries’ participation. We’ll share contributed examples and discuss how the MDG might help this effort along for IU and the Hydra community.
At the Metadata Discussion Group meeting on March 8 April 5, 2016, we will talk about some of the challenges of mapping a descriptive metadata structure standard (in this case, MODS) from a XML-based expression to one that is RDF-based. This post will explain what MODS is and what it’s used for.
MODS: the ‘Who, What, and When’
The Metadata Object Description Schema (MODS) was published in 2002 by the Library of Congress’ Network Development and MARC Standards Office. The standard is maintained by an editorial committee comprised of library metadata practitioners from North America and Europe.
MODS is a “bibliographic element set” that may be used to describe information resources. MODS consists of 108 elements and subelements (there are 20 top-level or “parent” elements). At this point, I’ll urge you to go read the brief overview of MODS on the Library of Congress’ Standards website.
Go ahead. I’ll wait.
You read that bit about MODS being more or less based on MARC21, right? In the example below, I’ve described a sheet map using MODS elements and MARC tags.
DATA (formulated according to AACR2, if that sort of thing matters to you)
MARC TAG (and mapped MARC data value, when applicable)
Campbell County, Wyoming
Campbell County Chamber of Commerce (Wyo.)
Campbell County Chamber of Commerce
1 map ; 33 x 15 cm
Table 1. Data expressed in MODS elements and MARC tags.
There’s a full mapping of MARC21 tags to MODS elements available, if you’re really curious. This example demonstrates that, although there are a few divergences, MARC21 was built to map almost directly into a MODS element.
MODS encodes descriptive metadata, or information about resources (title, creator, etc.). MODS and MARC21 are examples of data structure standards. Elements or tags are meant to serve as containers for data. Structure standards do not give any directions about how to formulate data—those directions come from data content standards (AACR2, RDA, DACS, etc.). The main purpose for structure standards (Dublin Core, EAD, and TEI are other examples of metadata structure standards) is to encode data so that it can be manipulated by machines. Elements separate discreet information for use in search and browse indices. Data structure standard elements often convey the meaning of the data. The MODS:title element only contains the word or words that are used to refer to a resource. MODS:title will never serve as a container for the resource’s size.
MODS: the ‘Where, Why, and How’
MODS was built “for library applications.” MODS has been chiefly implemented to support discovery of digital library collections. At IUB Libraries, MODS is the metadata standard of choice for the digital objects that are ingested into our digital collections repository, Fedora.
MODS elements are expressed in XML. XML is a metalanguage, which means that XML is an alphabet, of sorts, for expressing other languages. The figure below illustrates the XML syntax (the “alphabet”) by which XML expresses another language. A fake language with a bogus element named “greeting” is encoded in Figure 1.
HTML (the language responsible for displaying this webpage to you right now), EAD, and TEI are also expressed using XML.
From the beginning, MODS was designed to be expressed as an XML schema. Schemata are the sets of rules for how languages work: which elements are valid and what their semantic meanings are, which elements nest within others, whether or not an element can be modified by attributes (e.g., the MODS:titleInfo might have an attribute called “type”), and whether there is a controlled list of values for a given attribute (e.g., the MODS:titleInfo “type” attribute is limited to the values “abbreviated, “translated,” “alternative,” “uniform”).
MODS records are created in a number of ways. You could open up an XML editor and start creating a MODS/XML record. If you want to really get to the know the MODS standard, that wouldn’t be a bad idea. However, if you wish to create metadata for a half a million photographs, editing raw XML won’t be terribly efficient. At IU, we have a few different methods for creating MODS records for digital objects. My favorite is the Image Collections Online cataloging tool. Use of the tool is restricted but I’ve included a screenshot below.
Once a collection manager decides which metadata elements are desired and has consulted with the metadata specialist for digital collections (our own Julie Hardesty), those elements will display in a web form. Data may then be entered without needing to know XML or MODS. In Figure 1, you’ll see a box in the lower right-hand corner “Transform metadata to…” Clicking on that link that says “mods” allows me to download the data that I input into the web form as MOD/XML. You may view the full record for this photograph below.
That’s the 5 cent tour of MODS, as it’s expressed in XML. Questions? Leave a comment below!
The Metadata Object Description Schema (MODS) Editorial Committee announced the posting of a draft MODS/RDF ontology. MODS, a descriptive metadata schema that is loosely based on MARC, is widely used to describe objects in libraries, archives, and museums. The new MODS/RDF ontology promises to usher MODS (and bibliographic data) into the realm of linked data. The MODS namespace has been under development for some time. The timing of the release of the MODS/RDF draft seems to be in response to the recent launch of BIBFRAME.org.
The MODS/RDF ontology homepage includes links to a primer, the MODS/RDF namespace document, and examples of MODS/RDF records. For those wanting to test drive the transformation of MODS/XML files to MODS/RDF, there is a stylesheet available as well.
The MODS Editorial Committee welcomes feedback on the draft ontology via the MODS listserv, where a number of MODS implementers have already commented on the draft.
MADS: Successful Linked Data Implementation
The MODS companion schema for authority data, Metadata Authority Description Schema (MADS), has already been published as linked data via the Library of Congress Linked Data Service. Click on the screenshot below to go to the authority record.