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We all use a range of strategies to find information. Information technology offers some new approaches, but these need to be seen as part of a broader vision.
In our daily lives we are constantly taking in and giving out information: a driver asks for directions, a shopper reads a package label, a mother seeks child care advice, a gardener compares pesticide data, an investor evaluates a company's performance. Most of the time, our information comes from sources we have used many times before. We know what we are doing; we know what we are getting.
Problems arise when we need information but we do not have trusted and familiar sources. We may be searching for the technical details to understand a geospatial data set. We may be looking through news reports from a foreign country. Or, a familiar information source moved to the Internet and now we need to learn how to use the new system.
This is the essence of the "information discovery" problem--we need information but we cannot retrieve it because we do not know who might have it or how to ask for it. The key to solving this problem is to envision a comprehensive yet simple way for people to discover information and know what it is and how to get it. The approach outlined here is as new as the Internet yet as familiar as a traditional library.
How would you find something in a warehouse? You might crawl around and look at the packaging of the containers. This is fun if you are just browsing. However, it is not a very good approach if you want to find a particular thing. In practice, most packaging is of limited use when you are looking for content. You need some kind of label that describes what is in each container.
We can think of information as packaged in containers. People label information containers in various ways to make them easier to locate. On your word processor, you assign a title and keywords to documents that contain information. Through its card catalog, a library labels books that contain information. Any of these information locators can be very useful, and we can even generate labels for most of the information content available electronically. The problem is, even where locators exist, you can search only some of the catalogs, directories, and other locators in a common way.
The Internet provides access to an amazing quantity of information. Internet-wide search services index hundreds of millions of Web pages. However, people cannot discover what they need unless the information is somehow organized. One approach is to make a huge pile of all the pages and create a giant index. Many services also classify the pages in various and innovative ways. Yet, few of these services today actually work with each other. Most Internet services have yet to agree on standards comparable to what libraries achieved many years ago.
Imagine the Internet as a series of information services, special libraries, museums, and archives with many catalog and indexes all working together to help us discover information. Anyone could create and operate such catalogs, as simply as making a Web page. The catalogs could be designed for a choice of languages and skill levels, and could focus on specific topics or places. A search could span not only an index of millions of Web pages but catalogs and indexes covering most of the world's libraries, atlases, directories, and databases. And, anyone who has used a library would be already know how it all works.
The GILS vision adopts bibliographic as well as networking and computer technologies. Enlightened by information policy values, these ideas create a powerful new synthesis..
This vision of global information discovery enabled by common standards is known as the "Global Information Locator Service" (GILS). GILS adopts a mature international standard for searching labeled information. This standard developed primarily in the library and information services communities. Today, it is in worldwide use on Internet and other networks, making GILS interoperable with the largest and most valuable information resources available anywhere.
There are many ways to help people find information, but some are better to enhance the free flow of information. While it leverages common practice, the GILS standard does not enforce any particular format and it avoids having a central authority or other fixed relationships. All kinds of people and organizations worldwide can independently offer all kinds of locators. All that comply with GILS are directly searchable. Also, the design of GILS accommodates the fact that networks are not the way to reach all audiences. Sometimes, a printed book or newsletter is the best media for helping people find information. A telephone referral service or face-to-face contact is best in yet other situations.
The idea of metadata has been compared to bibliographic citations, but the concept can be applied very generally. We can say that any information is distinct only insofar as it has distinguishing characteristics and "metadata" is the generic term for data that characterizes any kind of information. Packages have label metadata, people are characterized by biographical metadata, electronic data has attribute metadata, and many kinds of objects and artifacts have property metadata.
In the case of a computer file, we can find metadata such as name, owner, creation date, and format. The metadata may be embedded within the file, as in a word processing document or a Web page with an embedded title. The metadata can also be maintained separately, as a library catalog record is separate from a book. Either approach can be accommodated from an information discovery perspective. It is only necessary that metadata is somehow associated with the information it characterizes.
The information discovery perspective provides another important simplification with regard to metadata. While there are many hundreds of different characteristics in use for bibliographic cataloging and related disciplines, only a few characteristics have been routinely used for information discovery, i.e., Title, Author, Subject, Date, and Place. Not surprisingly, these few characteristics are traditionally used for citations of books and are the same characteristics now found most commonly in metadata on the World Wide Web.
Once we have generalized metadata to encompass characteristics of all manner of information and then focused on those few characteristics commonly used for discovery, the global information discovery problem begins to appear tractable. Yet, we are still faced with daunting diversity in the ways that these few metadata elements appear across information types, across languages, and over time. To arrive at the commonality among metadata, we need to see past the form of the metadata into its meaning-an abstraction process known as "semantic mapping".
Consider the case of searching across three different information collections: book citations, news articles, and electronic mail messages. If the searcher wants to search by "title," only the book citations have exactly this form of metadata. However, the provider can decide that other metadata have similar meanings to the concept of "title." In the news articles, the provider might decide that "headline" is almost the same as "title." In the electronic mail collection, the closest metadata for "title" might be "subject line".
Semantic mapping refers to the drawing of equivalence between related concepts. In the context of information discovery, the beauty of semantic mapping is that searchers do not need to know each of the names used for metadata in each of the different collections. Searchers only need to know the common concepts. Also, with the semantic mapping approach, providers avoid having to force metadata into any particular format. Content providers can actually assemble metadata as needed from various sources and offer searchers a choice of formats. Providers may also choose to map search concepts in different ways for different audiences, e.g., search specialists may see a complex tool while children get a simple one.
In the same way that information on a library card catalog record helps to locate a book, any metadata can be used to locate information. We can think of information discovery in terms of finding a locator record that describes the information we need. Such a locator record is defined by its use, not its form or content. A locator record may be as simple as an Internet address, or as complex as a User's Guide.
A locator record can characterize anything--Web resources, books, e-mail, people, meetings, artifacts, genetic codes, datasets, projects, organizations, etc. On the Internet, a locator record for a Web page typically includes both the visible content and the embedded metadata. A locator record for an Internet service may address more complex and contextual metadata such as privacy protections, authentication information, external references, and the Internet domain registration. Things without online content can still have metadata. For example, a person's locator record may include an address and photograph while a locator record for one flower in a collection may have metadata for characteristics such as species name, collector, date, and place.
Interoperability in searching across different types of information is the central feature of GILS. By virtue of the semantic mapping of search concepts, any information search service can offer a high degree of interoperability. A single search service can handle locator records that vary across format and language. Records may be distributed across the Internet or even within other catalogs, directories, and databases. To find my local grocery store, an intermediary search service can search across entries in a telephone database, maps in an atlas of my neighborhood, and an index of Web pages. Content or metadata from different sources are then presented as appropriate in response to my search request.
Semantic mapping and locator records together make for an elegant and powerful search service. However, a searcher also needs to know the specific set of search concepts actually supported. GILS-compliant search services always support a specific minimum set of search concepts, and these concepts are all traditional bibliographic concepts from a long tradition of cataloging. Bibliographic communities worldwide agreed on the Machine Readable Cataloging standard about thirty years ago. They have also created mechanisms to search library catalogs on the Internet. Because GILS adopts its search concepts from these mechanisms, GILS interoperability encompasses the accumulated knowledge represented in many millions of bibliographic records worldwide.
Worldwide, hundreds of overlapping information communities are using GILS. Many information communities use the search interoperability of GILS without further specification, but some have added extensions for their particular needs. A common approach is to add Usage Guidelines to specify rules about the information content shared across an information community. For example, a Usage Guideline may specify organizational responsibilities, how frequently the metadata should be updated, or whether a particular metadata element is mandatory or needs to be coded in a certain way.
While GILS gives a minimum set of common concepts, there is no limit to extending the interoperability. An information community focused on popular music can supplement their GILS support with online lyrics and directories of artists and events. Music searchers might use a "Web gateway" to search among these various resources, but through GILS the gateway extends the community's information to related communities and libraries. The music community might also extend the gateway with a new "search-by-sound" feature. This feature would simply co-exist with the GILS interoperability. Later, the community might make this new feature interoperable across communities as well. With GILS as a solid foundation, communities can build whatever interoperability they need.
A community may be defined as people sharing common characteristics or interests. The sharing of information itself can define an information community.
Information communities communicate with media such as newspapers, bulletin boards, e-mail, and Web sites. Some members act as information community organizers--intermediaries who select sources and turn raw data into relevant information. An information community may be formal or informal. It may be long-standing or as fresh as the latest entertainment event.
Organizations typically participate in a primary information community, but each is likely participating in other information communities as well. In many cases, trust is a binding factor for information communities. As friends and relatives are more trusted than strangers, we value information from trusted sources more than from anonymous ones. At any scale, from the smallest information community to our Global Information Infrastructure, trust depends on people evaluating their information sources. To evaluate an information source, whether the content is geospatial data or any other type of information, people need contextual information about each provider and each service in addition to mechanisms for searching the content.
Information communities understand and organize their own information. These organizations are in the best position to manage their information over the long term. Yet, intermediaries and secondary users have needs, too. They need to find information across communities.
GILS resolves this conflict. For example, one collection may have hundreds of bibliographic records with precise metadata. Another collection may have thousands of machine-generated Web page metadata that is much less precise. Using GILS, there is no need to "dumb-down" the more precise metadata to support cross-domain searches.
This diversity in the GILS vision is different from traditional cataloging. Bibliographic records that use fixed cataloging rules are quite standardized. GILS locator records, in contrast, can be very different from each other. Even where metadata is held in the same format, different organizations may have different policies. For example, two communities may both have "Contact" metadata about information resources. One community may insist that the Contact should always name a person. Another community may insist that the Contact always name an organization. Even where the content seems identical, each collection may be quite distinct in the context it provides. Locator record metadata for "Quality" can be quite different between a scientific information community and a politically oriented information community.
What metadata is required and how it is organized depends ultimately on the interests and resources of the communities. Some communities may standardize certain metadata content across their GILS services. For example, there may be standardized spellings for names or a controlled list of subject terms. However, any such standardization increases coherence at the expense of diversity. Each community may choose a different balance, and various collections of GILS locator records end up being quite distinct. This is a primary reason why the GILS vision focuses on distributed Internet search rather than standardizing on a networked "union catalog."
Over the past 150 years, those who work with bibliographic information have organized an effective international community. This international community deals extensively with standards for information access and has extensive programs for professional training and research, often described as Library and Information Science. Cataloging standards are commonplace throughout this community and are also used extensively in related disciplines and communities such as museums, archives, records management, document management, abstracting and indexing, thesauri, and information retrieval. Because GILS adopted their catalog search standard, GILS is interoperable with the bibliographic community and its thousands of massive information treasure houses worldwide.
The international community versed in Geographic Information Systems has developed only in the past few decades. This community gained an early and abiding interest in metadata, so that the sharing of metadata among geospatial projects and software vendors is now well standardized. The search standard for geospatial metadata worldwide is the Geospatial Profile, built on GILS but specifying more precise searching for data referenced to places on the Earth. Many other national and international systems also follow this standard, including the Global Spatial Data Infrastructure, the National Biological Information Infrastructure, the International Directory Network of the international Committee on Earth Observing Satellites, the Global Change Data and Information System, and the Global Earth Observations System of Systems, among others.
There is a wide range of information communities dealing in various ways with environmental data, information, and metadata at levels raging from small-scale disaster management to worldwide environmental treaties. For example, the biological community is challenged to organize millions of plant and animal species data sources. They also share an amazing variety of information resources, including species taxonomies, laws, monitoring data, events, expertise, tools, models, educational materials, and journal articles, among many others. Much of the environmental information community is building upon GILS and the Geospatial Profile to support search access across this far- flung and diverse set of information communities.
Governments themselves comprise a set of information communities, with many and complex relationships among component organizations and across governmental levels. The U.S. Federal Government was an early adopter, requiring GILS under law and policy to support public access to government information. Similar initiatives have been undertaken in other nations as well as dozens of U.S. states and cities. These governmental GILS initiatives are strongly associated with other information communities, especially geospatial, libraries, records management, and environmental communities.
GILS begins with a bibliographic foundation but embraces the wide diversity found among information communities. Searchers, information providers, and intermediaries each have different reasons for supporting GILS.
For information users, GILS provides a standard way to find information resources by their characteristics. That information resource may be a specific document, an information service, a collection of information, or an entire organization. Having a common standard allows searchers to find information across institutions separated by geography, charter, focus, or government. Because GILS adopted standard bibliographic concepts, anyone who understands a book citation or a library catalog already knows the concepts used in GILS.
When used to describe broad information collections, GILS locators communicate the basic essentials of the content of an information collection. Searchers use GILS records to navigate quickly and easily to the collection of interest. Within a collection, searchers may find an individual item or may choose to find referrals to other collections. This ability to chain referrals one after another allows searchers control that is more precise. For example, if a searcher wants specific information about buying a used car, the first step should be to get referrals to the information communities that deal with used cars. The set of collections with used car information is likely then to support searching on used car characteristics such as price range, makes and models.
GILS defines a search service only at the level of computer to computer communication. The design of user interfaces for searching is outside the scope of GILS and there are no constraints on presenting the service to searchers. GILS simplifies the way an content provider or intermediary offers content to a wider audience and exploits content accessible elsewhere. Most searchers are unaware when GILS is being used. In fact, some searchers are not people but software "agents" gathering search results for later use.
GILS defines an open, low-cost, and scalable standard. Communities, governments, companies, and other organizations use GILS to help searchers find information through metadata. Content providers or intermediaries insert descriptive metadata into Web pages or word processing documents, organize metadata using database technologies, or manage metadata as documents in their own right. They offer metadata search over the Internet through GILS-compliant software. Products include Internet search engines like Alta Vista, DOCS-Fulcrum SearchServer, MetaStar, Ultraseek, and Netscape Compass. There are GILS add- ons for database systems like Oracle, and MS-SQL. Of course, libraries can choose among catalog systems like SIRSI, Dynix, and Voyager. Providers can also choose free GILS software from several sources around the world.
Intermediaries will be interested in using the thousands of sources available through this standard interface, many of which are free on the Internet. Many of these contain millions of bibliographic references and other information--whether free sources such as the Library of Congress and the National Library of Medicine or the hundreds of commercial information services.
GILS is also seen as a standard interface that helps make information systems more modular. Inserting a GILS-compliant interface into a system allows the system architect to separate the search engine from the network and other components. As reflected in the latest generation of database systems and standards, having such an interface is important when different indexing approaches are required, such as geographic indexing compared to text or multi-media. A standardized interface is also useful whenever one needs to migrate system components to new technology or different software vendors. Individual systems can be replaced ded rather than having to replace a complex set of intertwined subsystems.
GILS provides a powerful standards-based approach for deploying an "information locator service" designed to identify and describe information resources and to assist searchers in obtaining the information. In addition to online information delivery, this approach for locating information can include other media and various value-added features and dissemination services provided by intermediaries in all sectors of society. It can also span all aspects of content management, including data management, information management and knowledge management. With network technologies such as the Internet, an implementation of GILS can be: focused or comprehensive, interoperable without being restrictive, and coherent without being centralized.
Although this vision of global information discovery is powerful, it is important to recognize that an information locator is just one part of an overall information infrastructure. An information infrastructure encompasses the entire framework of facilities, institutions, and policies supporting information throughout a community. In the simplified "information life cycle" diagram below, information is regarded as progressing through six stages. GILS focuses on the "discover" stage where information already exists in an accessible form but needs to be discovered so that it may be used.
Software for implementing GILS systems is available in freeware as well as commercial products.
The choice of software is largely a function of the type of information resources to be interfaced and what software is available and affordable. There are a range of options available to accomplish the mapping for a GILS-compliant gateway for many search engines, FTP facilities, E-mail files, and other sources.
In the simple case, one can add to any Web page a link to a GILS-aware search gateway supported elsewhere on the Internet. That gateway would support distributed search of many other collections, with some provision for handling the multiple sessions and combing results. One can also offer a more customized search facility, such as a GILS-aware "search portal" designed specifically for a particular audience. Customization can then be made on the particular databases to be searched, the look and feel of the search interface, the kinds and extent of search fields offered to achieve precise search results, the language in which the search page is presented, and so on.
For more information on search portals see </portals.html>
It is a simple matter to map GILS onto a database that already supports the GEO or CIP profiles of Z39.50, as these are supersets of the GILS Profile. Information sources that have the search characteristics of databases can connected through a Z39.50/ODBC Gateway, where ODBC exposes the search facility as an application programming interface (API). There are also mechanisms to provide a GILS interface with systems that use the LDAP interface, Microsoft Active Directory, Lotus Domino, WebDAV/DASL, and various other interface specifications. As might be expected, the gateway task gets more complex where non-standard database technologies are in use. For databases already exposed on the Internet, there are tools to link the GILS interface into facilities implemented with "Common Gateway Interface" and possibly other technologies. Of course, interface driven only by custom program code will likely need a custom program interface for GILS.
Software products for building GILS-compliant servers include: Internet search engines like Alta Vista, DOCS-Fulcrum, and Ultraseek; database systems like Oracle and Microsoft Access; and traditional library catalog systems like SIRSI. In addition to complete GILS-compliant server solutions, there are many sources of GILS software component products and developer toolkits for all popular platforms and in various languages including C, Perl, and Java. Freeware sources include the Advanced Search Facility and IndexData. Commercial products are available from many vendors including Basis Systems Netzwerk, Blue Angel Technologies, Compusult, Crossnet Systems, and IndexData.
For more information on toolkits and server software, see </software.html>
At the level of standards and technology, GILS defines a certain set of Internet search requirements. Although it can be extended to serve various other information communities, the basic set is sufficient for many purposes.
The international standard for information search is ISO 23950 "Information Retrieval Application Service Definition and Protocol Specification for Open Systems Interconnection" (identical to the U.S. national standard ANSI/NISO Z39.50). The standard supports full-text search but also supports large, complex information collections.
The GILS standard is an international standard profile of ISO 23950. It specifies how to express a search and return results. It does not specify how network servers manage records or how clients use records.
GILS specifies an interface at the server side of a client-server interconnection over the Internet. At this interface, a GILS-compliant server interoperates in specific ways with client software A GILS-compliant server operates like a bibliographic catalog, but GILS uses only a few of the many optional specifications in the catalog standard. Most systems for searching bibliographic catalogs can search GILS servers and systems built to search GILS servers can search most bibliographic catalogs. Servers compliant with the ISO 23950 Geospatial Profile (GEO) or the Catalog Interoperability Proifle (CIP) are also compliant with the GILS standard.
The standard for searching bibliographic catalogs is one of several standards for network searching. Database searching is largely standardized on Structured Query Language (SQL). Directory search uses the Lightweight Directory Access Protocol (LDAP) standard. Other standards address searching document properties and content, including current work on the Extensible Markup Language (XML). Systems have demonstrated interoperability using GILS in combination with these and other network standards. GILS has also been used with Open Systems Interconnection and object-oriented architectures (e.g., CORBA) on the desktop and local networks, as well as directly over the Internet and with HyperText Transfer Protocol (HTTP). At present, it appears that the GILS standard search mechanism can be used in any operating environment and is well positioned to evolve with future network information discovery developments.
Client software to exploit GILS servers may be implemented within a single-user desktop application or as part of a gateway or other facility that handles interaction with multiple servers or protocols. The client-server interface specified in the GILS Profile is completely independent of any user interface and is therefore compatible with not only browsers but with other kinds of automated processing.
At the server side, the GILS interface is also independent of any specific database model or structure, and of the specifics of search engine implementations. This means that GILS is compatible with most databases, file systems, electronic mail, document management, and other methods of managing data, information, and knowledge.
The GILS interface is an Internet client-server protocol specification, as are the Hypertext Transfer Protocol (HTTP) and File Transfer Protocol (FTP). The GILS interface specifies how an Internet server supports a search service. In addition to some common Internet facilities, the GILS interface requires specific server responses for each of the three specified client request messages: Init, Search, and Present. The "Init" request/response messages communicate the protocol version and certain other session parameters. The "Search" request/response messages communicate a standard search vocabulary and syntax, including references to standardized search attributes with registered semantics. The "Present" request/response messages provide the machinery to deliver specific result records from the set of records that satisfied the search.
GILS-compliance requires the usual comparison operations ("less than", "greater than", "equal to") applied with dates, words, and phrases. It also requires the server to handle nine concepts: Title, Originator, Distributor, Record Source, Subject Terms--Controlled, Subject Terms--Uncontrolled, Date Last Modified, Any (i.e., "full-text"), and Local Number.
Following the principle of semantic mapping, the GILS interface provides a base of common search attributes that the public can use when searching. For any databases to support a GILS search interface, there needs to be a "map" relating these common characteristics to whatever fields are available in the database. For example, if a particular database has records each with the fields "Data Set Name" and "Owner", the database administrator might map the field "Data Set Name" to the search attribute "Title", and the field "Owner" to the search attribute "Originator".
The following semantics are registered in the ISO Basic Semantic Registry for the concepts used for search in the GILS Profile standard (these are known in ISO 23950 as "Use Attributes"):
Title: The name given as the distinctive designation of the information resource.
Local Number: The local number of the locator record of the information resource.
Originator: An organization or a group of persons that is identified by a particular name.
Date Last Modified: The date of last modification of the locator record of the information resource.
Distributor: The name of the person acting as distributor of the information resource product.
Subject Terms--Controlled: The controlled vocabulary associated with the subject of the information resource.
Subject Terms--Uncontrolled: Subjects headings defined locally.
Any: The record is selected if there exists a Use attribute that the target supports such that the record would be selected if the target were to substitute that attribute.
Anywhere: The record is selected if the term value (as qualified by the other attributes) occurs anywhere in the record.
West Bounding Coordinate: The value of the western- most coordinate of the location of the coverage of the information resource.
East Bounding Coordinate: The value of the eastern- most coordinate of the location of the coverage of the information resource.
North Bounding Coordinate: The value of the northern- most coordinate of the location of the coverage of the information resource.
South Bounding Coordinate: The value of the southern- most coordinate of the location of the coverage of the information resource.
The table below shows the combinations of attributes specified for a GILS-compliant server. GILS-compliant servers must respond to search requests that include three kinds of attributes: Use Attributes, Structure Attributes, and Relation Attributes. For example, to find documents with "USGS" in the Title, a search request would specify that the Use Attribute is "Title", the Structure Attribute is "Word" and the Relation Attribute is "Equal". At the protocol level, each attribute is identified by its assigned number as registered in the Attribute Set in force for the session. In addition to the Geospatial Profile, all attributes needed for GILS-compliance are registered in the Bib-1 Attribute Set and the GILS Attribute Set (both of these Attribute Sets are part of the ISO 23050 version 2 standard).
|Title||Word, Word List||Equal|
|Local Number||Word, Word List||Equal|
|Originator||Word, Word List||Equal|
|Date Last Modified||Date||Greater Than, Equal|
|Record Source||Word, Word List||Equal|
|Distributor||Word, Word List||Equal|
|Subject Terms-- Controlled||Word, Word List||Equal|
|Subject Terms-- Unontrolled||Word, Word List||Equal|
|Any||Word, Word List||Equal|
|Anywhere||Word, Word List||Equal|
|West Bounding Coordinate||Coordinate||Less Than, Less Than or Equal, Equal, Greater Than or Equal, Greater Than, Not Equal|
|East Bounding Coordinate||Coordinate||Less Than, Less Than or Equal, Equal, Greater Than or Equal, Greater Than, Not Equal|
|North Bounding Coordinate||Coordinate||Less Than, Less Than or Equal, Equal, Greater Than or Equal, Greater Than, Not Equal|
|South Bounding Coordinate||Coordinate||Less Than, Less Than or Equal, Equal, Greater Than or Equal, Greater Than, Not Equal|
|From a data store perspective, it is useful to think of the GILS interface as an additional gateway. On the Internet, this is like supporting FTP access to a collection of data in addition to supporting HTTP access. The GILS interface would typically occupy a different port on the same server, though it can also be located on another server if desired. The well-known port number for Z39.50/GILS/GEO/CIP is "210" and there can be any number of "databases" at the port.|
An administrator of a GILS server will need to decide at the semantic level how to map the search attributes available in GILS to the fields available in the database. Some of the fields may be obvious (e.g., Any/Anywhere should probably be targeted at any available text fields; Bounding Coordinates should be mapped to lat/long if available), while others may have no appropriate mapping at all. Another decision involves what output is to be delivered when the searcher gets a "hit". There should be at least two levels of output--a "brief" record suitable for display as an item in a "hit list", and a "full" record to be delivered when the searcher selects that record from the hit list.
It is probably not a good idea for the administrator to make these decisions alone. The best approach is to define a simple mapping and see whether real searchers find it useful. Throughout the prototyping, it will be important to involve searchers outside of the usual primary audience. After all, the primary audience is likely already being served well by the interfaces specifically built for their needs. The GILS interface provides the opportunity to help "everyone else" find information.
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