Metadata: an overview of current resource description practice
Work Package 3 of Telematics for Research project DESIRE (no. 1004)
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Title page
Table of Contents
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The Government Information Locator Service (GILS) has a draft application profile (see <URL: http://www.usgs.gov/public/gils/prof_v2.html>) that is intended to be submitted to the Open Systems Environment Implementors Workshop/Special Interest Group
on Library Applications (OIW/SIG-LA). It has already had an Implementors Agreement approved by the OIW in May, 1994. The Federal Information Processing Standard Publication (FIPS PUB) 192 (see <URL::>) references the application profile. This speci
fies the GILS attribute set for Z39.50 for GILS servers and clients that support Z39.50 Version 2.
The GILS was setup by the US Federal Government in order to provide the general public and its own employees with a means for locating useful information generated by the many government agencies. As such its constituency of use is very broad; literally a
nyone is likely to be able to search for resources using GILS and many different agencies are likely to use a variety of staff to generate their part of the overall GILS framework. Originally GILS was intended to force each agency to provide a set of loca
tors that . However in reality some agencies are using GILS as generic metadata records for many resources and others are hardly using it at all.
GILS is a fairly complex metadata format, partly because of its breadth of coverage and partly because its design has been heavily influenced by the MARC and Z39.50 communities. Although it is possible that simple GILS records could be created by untraine
d staff, the format permits very rich and complex records to be created. As mappings to/from USMARC are provided in the GILS documentation it seems sensible to assume that at least some of the GILS records will be derived from USMARC records, which are th
emselves quite complex to create correctly.
The GILS concept builds upon many international standards and has resulted in the creation of the GILS profile for the Z39.50 servers and clients. This is gaining some support, mainly as a result of pressure from the US government, but is not nearly as wi
dely implemented and deployed within the Z39.50 community as say BIB-1. Indeed, many of the targets linked to from the GILS information pages (see <URL: >) are just straight library catalogues with Z39.50 servers returning only MARC or SUTRS records
and aren't even run by a part of the US Federal government. In the GILS community these servers are said to be providing
A number of other governments, such as the Canadian and Australian governments, are looking at the work done by the US GILS programme. Whether these are adopted on a large scale and what importance they will have in the future information society remains
to be seen.
The information for this section is extracted from Annex E of the . This defines all of the elements in the GILS Core Element Set. These elements are defined as either being repeatable or not repeatable; the repeatable elements may appear more than once i
n a single GILS record whereas the not repeatable elements can only appear zero or one times.
Some of the elements are constructed from two or more subelements. For example, the Controlled Subject Index element is a grouping of subelements for Subject Thesaurus and Subject Terms Controlled. The grouping can be nested and is in
this case; Subject Terms Controlled itself is a group formed from a repeatable subelement called Controlled Term.
The basic decriptive (biblographic) elements included in the GILS Core Element set:
• Title
• Author
• Date of Publication
• Place of Publication
• Abstract
• Agency Program
• Resource Description
The subject description elements included in the GILS Data Element set are:
• Controlled Subject Index
• Subject Thesaurus
• Subject Terms Controlled
• Subject Term Uncontrolled
• Controlled Term
• Local Subject Index
GILS Data Element records use the Availability Linkage and Availability Linkage Type data elements to specify the URI and MIME type respectively of the resource that the record is pointing at. These fields may be repeated within a single GIL
S record. There is also a set of Cross Reference elements that are used to refer to other, related GILS records. This set contains the Cross Reference Linkage and Cross Reference Linkage Type elements that indicate the URI and MIME ty
pe of the related record. The Cross Reference elements can also be repeated.
The resource format and technical characteristics and prerequisits are detailed in the following GILS Data Elements:
• Availability Medium
• Technical Prerequisites
GILS Data Elements contain a number of fields to provide contact information. These include:
• Point of Contact
• Contact Name
• Contact Organization
• Contact Street Address
• Contact City
• Contact State or Province
• Contact Zip or Postal Code
• Contact Country
• Contact Network Address
• Contact Hours of Service
• Contact Telephone
• Contact Fax
The administrative metadata required to maintain a GILS record is held in the following GILS Data Elements:
• Date of Last Modification
• Record Review Date
• Originator
• Control Identifier
• Original Control Identifier
• Record Source
• Schedule Number
The GILS Core Data Element set provides the following elements for dealing with issues of provenance and record/resource data source.
• Purpose
• Availability
• Distributor Name
• Distributor Organization
• Distributor Street Address
• Distributor City
• Distributor State or Province
• Distributor Zip or Postal Code
• Distributor Country
• Distributor Network Address
• Distributor Hours of Service
• Distributor Telephone
• Distributor Fax
• Sources of Data
• Record Source
Terms of availability and legal restrictions on records and resources (including but not limited to copyright) are included in the following elements from the GILS Core Data Element set:
• Availability
• Order Process
• Order Information
• Cost
• Cost Information
• Available Time Period
• Available Time Structured
• Available Time Textual
• Access Constraints
• General Access Constraints
• Originator Dissemination Control
• Security Classification Control
• Use Constraints
The definitions of the GILS Data Elements is given in Annex E (GILS Core Elements) of the GILS Application Profile. There is also a U.S. National Archives and Records Administration publication called "Guidelines for the Preparation of GILS Core Entr
ies"
(see <URL: >). This is intended to specify which elements are mandatory in specific contexts within the US Federal Government, and also gives examples of customary usage of specific elements.
It should be noted that it is also permissible to use locally defined elements within GILS records in addition to the GILS Core Element set. Some of these elements may themselves be well known elements in other Z39.50 application profiles or other informa
tion systems.
GILS Data Elements are available in an extended attribute-value pair format and the GILS Application Profile also provides a mapping to and from USMARC Tags and GRS-1 record syntax.
For physical transfer a GILS record may be delivered as a USMARC, GRS-1 or SUTRS record according to the GILS Application Profile. There may of course be further transfer encodings applied to these basic formats to allow the records to be sent through hos
tile environments. For SUTRS records, the GILS documentation defines an explicit prefered ordering to the output of the attributes so that the elements near to the top of the record are the ones that most readers will use to choose whether the record is u
seful to them. However servers and clients are free to provide other orderings in addition to the preferred ordering.
The GILS Data Element set contains an element called Language of Resource that indicate the language of the resource that the record points at. There is also a Language of Record element that specifies the language that the GILS record itsel
f is written in. Both of these are defined in the GILS Application Profile to be in the USMARC three character alpha code.
The Cross Reference elements of the GILS Element Set provide the ability for GILS records to record relationships between themselves. The Cross Reference element subsets are also intended to be used inside Controlled Subject Index Subject
Thesaurus structures to describe where to acquire and reference the thesaurus.
GILS is best described as being fairly high on the scale of fullness and complexity. For example in addition to all the elements described above for dealing with Document Like Objects (DLOs), it also contains a number of elements subsets for dealin
g with simple geospatial and temporal metadata. However it does not offer the range of specialised metadata formats that some of the more advanced geospatial applications require, such as percentage cloud cover.
The USMARC, GRS-1 and SUTRS record syntaxes that GILS servers support are not tied to any one transport protocol. However most GILS implementations are using TCP. The use of other transport protocols is specifically undefined in the GILS Application Profi
le draft. In some ways this is a little surprising as the US Government, in common with many other governments, was pushing OSI protocols for internal use very strongly until a few years ago and one would have expected them to have some legacy systems tha
t only understand one of the OSI transport protocols.
GILS servers are often implemented using Z39.50 servers, although this does not appear to be mandated absolutely as some US Government institutions are providing their GILS records by other means such as WAIS and HTTP. Some agencies are using the GILS rec
ords to generate HTML documents suitable for browsing by WWW browsers and some have either provided CGI front ends to their Z39.50 servers or loaded the records into another web accessible database in order to allow users to search their resources using a
normal WWW browser.
Most US Federal Government agencies now have GILS records deployed, and it is use is being investigated by serveral other governments. Funding and encouragement from the US Government is also causing several companies, such as AOL and WAIS Inc, to start d
eveloping GILS compliant Z39.50 servers. Some of these will be freely available, whilst others will be commercial products.