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Digital Mapping Techniques '02 -- Workshop Proceedings
U.S. Geological Survey Open-File Report 02-370

The National Geologic Map Database: A Progress Report

By David R. Soller1 and Thomas M. Berg2

1U.S. Geological Survey
908 National Center
Reston, VA 20192
Telephone: (703) 648-6907
Fax: (703) 648-6937
e-mail: drsoller@usgs.gov

2Ohio Geological Survey
4383 Fountain Square Dr.
Columbus, OH 43224
Telephone: (614) 265-6988
Fax: (614) 268-3669
e-mail: thomas.berg@dnr.state.oh.us

The National Geologic Mapping Act of 1992 and its reauthorizations in 1997 and 1999 (PL106-148) require that a National Geologic Map Database (NGMDB) be designed and built by the U.S. Geological Survey (USGS), in cooperation with the Association of American State Geologists (AASG) and other entities participating in the National Cooperative Geologic Mapping Program. The Act notes that the NGMDB is intended to serve as a "national archive" of geologic maps, to provide to a wide variety of people, from private citizens to professional geologists, the information needed to address various societal issues. The Act requires the NGMDB to also include the following related map themes: geophysics, geochemistry, paleontology, and geochronology. In this progress report, the term "geoscience" is used to refer to these five map themes.

In mid-1995, the general stipulations in the Act were addressed in the proposed design and implementation plan developed within the USGS and the Association of American State Geologists (AASG). This plan was summarized in Soller and Berg (1995). Because many maps are not yet in digital form and because many organizations produce and distribute geologic maps, it was decided to develop the NGMDB in several phases.

The first and most fundamental phase includes a comprehensive, searchable Catalog of all geoscience maps in the United States, whether in either paper or digital format. Figure 1a shows how the Map Catalog can be used to find a particular geologic map. Upon searching the NGMDB Catalog and identifying the needed map(s), the user is linked to the map data, the metadata, or to the appropriate organization for information about how to purchase the map. (The organization could be a participating state or federal agency, association, university, or private company.) The Map Catalog presently is supported by two databases developed under the NGMDB project: (1) GEOLEX, a searchable geologic names lexicon; and (2) Geologic Mapping in Progress, which provides information on current mapping projects, prior to inclusion of their products in the Map Catalog. In the coming year, an Image Library will be prototyped and made available to the public; this new initiative is described below. Plans for the prototype National Paleontology Database also are discussed below.

Figure 1. Diagram showing how a user might navigate the NGMDB Map Catalog and the online map database.

Diagram showing how a user might navigate the NGMDB Map Catalog and the online map database - part A

a. The user, interested in knowing something about the geology of an area (e.g., the land beneath his house), queries the Map Catalog, which returns a hit list of possibly useful maps. The user selects a map entry and, from the Product Description Page, obtains further information and can choose to either buy the map, view and download it, or inspect the metadata. The dark arrow toward the bottom of the figure points toward the online map database (Figure 1b).

Diagram showing how a user might navigate the NGMDB Map Catalog and the online map database - part B

b. The user queries the online map database. (Note: the paths along these queries are shown as dashed lines, to indicate planned development.) From the initial display showing the geology of the area surrounding his house, the user might choose to reclassify those units in order to derive a map showing engineering properties or query the geologic data in relation to external databases (here, an oil and gas database). Further, the user might be interested in the history of a particular geologic name or the availability of fossils; if so, the online map database would connect to GEOLEX or the National Paleontology Database.

The second phase of the project focuses on public access to digital geoscience maps, and on the development of digital map standards and guidelines needed to improve the utility of those digital maps. The third phase proposes, in the long term, to develop an online, "living" database of geologic map information at various scales and resolution. Some functions of the planned online database, and its links to databases developed under Phase One, are shown in Figure 1b.

In late 1995, work began on Phase One. The formation of several Standards Working Groups in mid-1996 initiated work on Phase Two. Progress was summarized in Soller and Berg (1997, 1998, 1999a, 1999b, 2000, and 2001). At the Digital Mapping Techniques '98 through '02 workshops, a series of presentations and discussion sessions provided updates on the NGMDB and, specifically, on the activities of the Standards Working Groups. This report summarizes progress since the project's inception, but focuses on accomplishments since mid-2001. Further and more current information may be found at the NGMDB project-information Web site, at http://ncgmp.usgs.gov/ngmdbproject/. The searchable database is available at http://ngmdb.usgs.gov/.

To submit general comments about project scope and direction, please address the authors directly (see above). For technical comments on the databases or Web page design, please use our Web feedback form; this form is linked from many of our search pages (e.g., see "Your comments are welcome," at http://ngmdb.usgs.gov/).

PHASE ONE

The project opened its Web site to the public in January 1997, as a prototype intended to solicit comments regarding the Map Catalog. Since then, and with public access to GEOLEX and the Mapping in Progress databases beginning in 1998, Web site usage has gradually increased. Since the time when essentially all USGS maps were entered into the Map Catalog, Web-usage statistics indicate that many users are visiting the site several times a month. This trend suggests that the site is becoming a more useful resource. Additional increases in use are expected as the Catalog and GEOLEX become fully populated and as the other NGMDB databases come online. Figure 2 shows the number of people (actually the number of unique IP addresses or computers) who have used the NGMDB since it opened to the public. (Note: Web "hits" are not shown in the figure, because they do not provide a realistic assessment of usage for sites like this. Further, the measure of unique IP addresses may in the future become a less reliable indicator, because increased security measures at some agencies are necessitating the use of dynamic IP addressing.)

Diagram showing web-usage statistics for the Map Catalog, GEOLEX, and Mapping in Progress Databases

Figure 2. Web-usage statistics for the Map Catalog, GEOLEX, and Mapping in Progress Databases. The Map Catalog accounts for roughly 75-80% of the usage.

The Map Catalog

The Map Catalog is designed to be a comprehensive, searchable Catalog of all geoscience maps of the United States, in paper or digital format. Entries to the Catalog include maps published in geological survey formal series and open-file series, maps in book publications, maps in theses and dissertations, maps published by park associations and scientific societies, maps published by other agencies, and publications that do not contain a map but instead provide a geological description of an area (for example, a state park). At the time of the DMT '02 conference, the Catalog contained a record for each of nearly 51,000 map products. Essentially all USGS maps have been recorded in the Catalog, and most state geological surveys are entering bibliographic records for all their maps and related maps (e.g., university theses). By the date of the DMT '02 meeting, geological surveys in 34 states were entering map records, as well as one University (Stanford). Maps by the Geological Society of America, the American Association of Petroleum Geologists, and numerous other publishers have been entered into the Catalog this year.

Soon after the DMT '02 meeting, the Map Catalog search page was extensively revised. It now addresses the diverse needs of our user audience through four search options (Figure 3). The easy-to-use Place Name Search is designed to address the needs of nongeologists who want to use a simple interface to find information about their home, town, or worksite, whereas the Comprehensive Search offers researchers a full range of search criteria.

New Map Catalog home page     Figure 3. The new Map Catalog home page, showing the four search methods -- Place Name, State Geologic Maps, Quick Search, and Comprehensive Search.

Geologic Names Lexicon

The searchable, online, geologic-names lexicon (GEOLEX) contains roughly 90% of the geologic names found in the most recent listing of USGS-approved geologic names (published in 1996 as USGS Digital Data Series DDS-6, revision 3) and is estimated to contain roughly 75% of all geologic names in the United States. Prior to loading into GEOLEX, the information on DDS-6 was consolidated, revised, and error-corrected. Our work now focuses on resolving name conflicts and adding reference summary and other information for each entry and on preparing the database for USGS Director's Approval as a standing database. Work remaining includes incorporating geologic names not found on DDS-6 but recorded in the geologic-names card catalog at USGS headquarters and names approved by the state geological surveys but not yet in the USGS records.

GEOLEX is intended to be the comprehensive, authoritative listing of approved geologic names and is available as a resource for geologic mappers nationwide. Many state geological surveys have been registering new geologic names with the USGS for decades and are encouraged to continue this practice under GEOLEX, through a Web-based application form.

Geologic Mapping in Progress Database

To provide users with information about current mapping activities at 1:24,000- and 1:100,000-scale (1:63,360- and 1:250,000-scale in Alaska), a Geologic Mapping in Progress Database is available at http://ngmdb.usgs.gov/MapProgress/MapProgress_home.html. This database will be linked to the quadrangle and county search capability of the Image Library (see below).

Image Library

Through discussions with users and from comments received via our Web feedback form, it has become clear that many people are interested in viewing and/or obtaining maps online. Interpretation of the phrase "providing maps online" varies widely -- to some people, it implies access to fully attributed, vector-based map databases, whereas to others, it implies access to map images. We address the enormous task of developing a vector-based map database in Phase Three (see below). Here, we address the potential for providing map images to users.

If we view the project's Map Catalog and online map databases (Phase 3) as endpoints on a spectrum of complexity and ease-of-use, it is obvious that a significant gap exists between them. The Map Catalog exists today; it is relatively straightforward to use and it simply provides bibliographic information about each geoscience map product. In contrast, the online map database is still in its formative, prototype stage; when publicly available, it will provide full access to detailed geologic-map information, but many users may not be sufficiently familiar with geoscience concepts to comfortably use it. This is a serious concern, as this project seeks to address the needs of all users, of various backgrounds and interests. As noted below, the AASG and USGS are working together to build the foundation for the online map database, through development of the necessary technology, science concepts and data model, and a collection of widely distributed digital geologic-map coverage.

In the middle ground along this spectrum, we have the opportunity to provide users with geologic-map information in a raster image format, thereby allowing them Web access to the familiar paper map format we've known for generations (Figure 4). Therefore, we have begun a new project initiative, to build a library of geologic map images. The images will be managed in high-quality compressed format, using MrSID technology. To deliver this information, we are beginning to design a prototype database and Web site to allow users to find and view geologic maps (Figure 5). At present, we anticipate providing the capability for searching by quadrangle (e.g., 1:24,000, 1:100,000, 1:250,000-scale) and by county. Our efforts will focus on providing images of general-purpose bedrock and surficial geologic maps.

Proposed Image Library

Figure 4. The proposed Image Library occupies a middle ground between the Map Catalog and the online map database in regard to technological complexity, ease-of-use, and related issues. It will provide users with geologic map information in a familiar image format.

Diagram showing how users could access the proposed Image Library to view high-quality images of published bedrock- and surficial-geology maps

Figure 5. Diagram showing how users could access the proposed Image Library to view high-quality images of published bedrock- and surficial-geology maps. The user would select a state of interest and then a quadrangle within that state; that selection would generate an information table that listed the available map products. For each map product, the table would provide links to the image ("View map . . .") and to the mapÕs record in the Map Catalog ("Map Description"). A user interested in purchasing a paper copy or downloading a digital version of the map can easily do so because the Map Catalog page includes the necessary information and links.

The Image Library will link directly to the Map Catalog and the Geologic Mapping in Progress Database. As evident in Figure 5, through these links we intend to direct users to the agencies producing the maps. We hope this initiative will further strengthen the cooperative relationship between the AASG and USGS.

Paleontology

The NGMDB project has designed and is planning to develop a national paleontology database (see Wardlaw and others, 2001). Our general plan is to build prototypes of this database in areas where geologic mapping is underway, so that we can work with mapping projects to design a database useful to science as well as to the public. A publicly accessible prototype is expected within the year.

PHASE TWO

Phase Two is directed mostly toward the development of standards and guidelines needed to help the USGS and state geological surveys more efficiently produce digital geologic maps and to produce those maps in a more standardized and common format among the various map-producing agencies. Significant progress has been made toward developing some of these standards and guidelines and to providing Map Catalog users with access to online products.

Standards Development

The following summaries concern activities of the AASG/USGS Standards Working Groups and their successors. General information about the Working Groups and details of their activities are available at http://ncgmp.usgs.gov/ngmdbproject/standards/.

Geologic Map Symbolization

A draft standard for geologic map line and point symbology and map patterns and colors, published in a USGS Open-File Report in 1995, was in 1996 reviewed by the AASG, USGS, and Federal Geographic Data Committee (FGDC). It was revised by the NGMDB project team and members of the USGS Western Region Publications Group and was circulated for internal review in late 1997. The revised draft then was prepared as a proposed Federal standard, for consideration by the FGDC. The draft was, in late 1999 through early 2000, considered and approved for public review by the FGDC and its Geologic Data Subcommittee. The document was released for public comment within the period May 19 through September 15, 2000 (see http://ncgmp.usgs.gov/fgdc_gds/mapsymb/ for the document itself and for information about the review process). This draft standard is described in some detail in Soller and Lindquist (2000). With assistance from a Standing Committee to oversee resolution of review comments and long-term maintenance of the standard, the document is being revised for submittal to FGDC for discussion and adoption as a Federal standard.

Digital Mapping

The Data Capture Working Group has coordinated six annual "Digital Mapping Techniques" workshops for state, Federal, and Canadian geologists, cartographers, managers, and industry partners. These meetings have been highly successful, and have resulted in adoption within agencies of new, more efficient techniques for digital map preparation, analysis, and production. The most recent workshop, held in Salt Lake City, Utah, and hosted by the Utah Geological Survey, was attended by approximately 100 representatives of 42 state, Federal, and Canadian agencies and private companies. The workshop proceedings have been published (Soller, 1997, 1998, 1999, 2000, 2001, and in this volume) and are online at (http://ncgmp.usgs.gov/pubs/of97-269/; https://pubs.usgs.gov/openfile/of98-487/; https://pubs.usgs.gov/openfile/of99-386/, https://pubs.usgs.gov/openfile/of00-325/, https://pubs.usgs.gov/openfile/of01-223/, and https://pubs.usgs.gov/openfile/of02-370/. Published copies of the Proceedings may be obtained from Soller or Berg.

Map Publication Requirements

Through the USGS Geologic Division Information Council, Soller led development of the USGS policy "Publication Requirements for Digital Map Products," enacted May 24, 1999. A less USGS-specific version of this document was developed by the AASG/USGS Data Information Exchange Working Group and presented for technical review at a special session of the DMT '99 workshop (Soller and others, 1999). The revised document, entitled "Proposed Guidelines for Inclusion of Digital Map Products in the National Geologic Map Database," was reviewed by the AASG Digital Geologic Mapping Committee. In 2002, it was unanimously approved via an AASG resolution and has been incorporated as a guideline for digital-map-product deliverables to the STATEMAP component of the National Cooperative Geologic Mapping Program.

Metadata

The Metadata Working Group developed its final report in 1998. The report provides guidance on the creation and management of well-structured formal metadata for digital maps (see http:// ncgmp.usgs.gov/ngmdbproject/standards/metadata/metaWG.html). The report contains links to metadata-creation tools and general discussions of metadata concepts (see, for example, the metadata-creation tools, "Metadata in Plain Language," and other helpful information at http://geology.usgs.gov/tools/metadata/).

Geologic Map Data Model

State and USGS collaborators on the NGMDB continue to serve as representatives to the North American Data Model Steering Committee (NADMSC), assisting in the process of developing, refining, and testing the North American Geologic Map Data Model. The NADMSC has now formed various technical teams to conduct specific tasks within a one-year period and longer time-frames. If interested, please visit the NADMSC web site at http://geology.usgs.gov/dm/. More information is provided in these Proceedings in the paper by the NADMSC's Data Model Design Team.

Access to Online Products

As standards are developed under Phase Two and via other mechanisms, the products released by geological surveys increasingly are standardized in format and content. A principal goal of Phase Two is to provide links from the Map Catalog to the more standardized of these products. Through searches of the NGMDB Map Catalog, users are directed to Web sites for perusal of selected online products. This feature of the Map Catalog is now available for USGS products served on USGS Regional Publications servers and on the USGS Clearinghouse node, and for state geological survey products. At the time of the DMT '02 meeting, more than 900 links exist to online map products and their metadata.

PHASE THREE AND INTEGRATION WITH OTHER ASPECTS OF THE PROJECT

Over the past few decades, significant advances in computer technology have permitted complex spatial information to be stored, managed, and analyzed to the satisfaction of a growing number of geoscientists. At the beginning of the NGMDB project, we judged that computer-based mapping was not a sufficiently mature discipline to permit us to develop an online database. Further, technology for display and query of complex spatial information on the Web was in its infancy and hence was not seriously considered by the NGMDB project as a viable means of delivering useful information to the general public. Now, six years after the project's inception, there exists sufficient digital geologic map data; sufficient convergence on standard data formats, data models, digital mapping practices, and field data capture techniques; and sufficient technological advances in Internet delivery of spatial information to warrant a research effort aimed at building a prototype, online National Geologic Map Database.

To design an online database, project personnel have held numerous discussions with geoscientists and the general public to gauge interest in an online database and to define its scope. Based on these discussions, it is clear that this database should be:

  1. built from edge-matched geologic maps at various scales,
  2. managed and accessed as a coherent body of map information, not just as a set of discrete map products,
  3. updated by mappers and/or a committee, "on the fly" when new information becomes available (i.e., a "living" database),
  4. standardized, adhering to a standard data model and with standard scientific terminology, and
  5. available to users via Internet browsers and common GIS tools (e.g., ArcExplorer).
The NGMDB project has begun a series of prototypes designed to build this online, "living" database; an introduction to the design approach is given in Soller and others (2000). In 1999, we designed some basic requirements for a prototype geologic-map database and tested our concepts using some newly developed digital data for the Greater Yellowstone Area of Wyoming and Montana (Wahl and others, 2000). That first prototype was presented for discussion at the Geological Society of America annual meeting in October 1999. The prototype was well-received, and plans were begun for a second prototype, with a more complex set of tasks. That prototype, conducted in cooperation with the Kentucky Geological Survey, is summarized in Soller and others (2001). We anticipate further prototypes that will advance our understanding of the technical and management challenges to be addressed in development of the operational system.

The online map database is being designed to integrate with other databases developed under this project. For example, a user accessing the online map database might identify a map unit of interest and then want to purchase or download the original, published map product, or inquire about fossils found within that unit or the history of the unit's geologic name. These user questions exploit the power and flexibility of the databases, and we anticipate building into the system the functionality diagrammed in Figure 6. As another example of the interaction of the various NGMDB phases, this diagram shows that a user might access the Map Catalog and identify a map of interest; the user might then purchase the map or link to a map server where the product can be downloaded. In the latter case, the arrow passing through "Standards Development" indicates that the NGMDB project's standards-development activities affect the content and format of products served.

Diagram showing user access to the various components of the National Geologic Map Database project and to related external databases and services

Figure 6. Diagram showing user access to the various components of the National Geologic Map Database (NGMDB) project and to related external databases and services. The three project phases and the relations among them are shown. Dashed arrows indicate planned relations.

The Geologic Map of North America

The NGMDB has supported development of the digital version of the Geological Society of America's (GSA) Decade of North American Geology Geologic Map of North America (GMNA). The project has provided funding and expertise for development of the digital files that will be used to print the map in order to engage GSA in a discussion regarding development of a GMNA map database. In the coming year, we will be prototyping the database design and beginning to populate it, in collaboration with GSA and interested national geological surveys.

ACKNOWLEDGMENTS

The authors thank the members of the NGMDB project staff and collaborators for their enthusiastic and expert support, without which the project would not be possible. In particular, we thank: Nancy Stamm (USGS, Reston, VA; GEOLEX database, and general support and guidance to the project), Ed Pfeifer, Alex Acosta, Dennis McMacken, Jana Ruhlman, and Michael Gishey (USGS, Flagstaff, AZ; Website and database management), and Chuck Mayfield and Nancy Blair (USGS Library; Map Catalog content).

REFERENCES

Soller, D.R., ed., 1997, Proceedings of a workshop on digital mapping techniques: Methods for geologic map data capture, management, and publication: U.S. Geological Survey Open-File Report 97-269, 120 p., http://ncgmp.usgs.gov/pubs/of97-269/.

_______ 1998, Digital Mapping Techniques '98 -- Workshop Proceedings: U.S. Geological Survey Open-File Report 98-487, 134 p., https://pubs.usgs.gov/openfile/of98-487/.

_______ 1999, Digital Mapping Techniques '99 -- Workshop Proceedings: U.S. Geological Survey Open-File Report 99-386, 216 p., https://pubs.usgs.gov/openfile/of99-386/.

_______ 2000, Digital Mapping Techniques '00 -- Workshop Proceedings: U.S. Geological Survey Open-File Report 00-325, 209 p., https://pubs.usgs.gov/openfile/of00-325/.

_______ 2001, Digital Mapping Techniques '01 -- Workshop Proceedings: U.S. Geological Survey Open-File Report 01-223, 248 p., https://pubs.usgs.gov/of/2001/of01-223/.

Soller, D.R., and Berg, T.M., 1995, Developing the National Geologic Map Database: Geotimes, v. 40, no. 6, p. 16-18.

_______ 1997, The National Geologic Map Database -- a progress report: Geotimes, v. 42, no. 12, p. 29-31.

_______ 1998, Progress Toward Development of the National Geologic Map Database, in Soller, D.R., ed., Digital Mapping Techniques '98 -- Workshop proceedings: U.S. Geological Survey Open-File Report 98-487, p. 37-39, https://pubs.usgs.gov/openfile/of98-487/soller2.html.

_______ 1999a, Building the National Geologic Map Database: progress and challenges, in Derksen, C.R.M., and Manson, C.J., eds., Accreting the continent's collections: Geoscience Information Society Proceedings, v. 29, p. 47-55, http://ncgmp.usgs.gov/ngmdbproject/reports/gisproc98.html.

_______ 1999b, The National Geologic Map Database -- a progress report, in Soller, D.R., ed., Digital Mapping Techniques '99 -- Workshop Proceedings: U.S. Geological Survey Open-File Report 99-386, p. 31-34, https://pubs.usgs.gov/openfile/of99-386/soller1.html.

_______ 2000, The National Geologic Map Database -- a progress report, in Soller, D.R., ed., Digital Mapping Techniques '00 -- Workshop Proceedings: U.S. Geological Survey Open-File Report 00-325, p. 27-30,https://pubs.usgs.gov/openfile/of00-325/soller2.html.

_______ 2001, The National Geologic Map Database -- a progress report, in Soller, D.R., ed., Digital Mapping Techniques '01 -- Workshop Proceedings: U.S. Geological Survey Open-File Report 01-223, p. 51-57, https://pubs.usgs.gov/of/2001/of01-223/soller1.html.

Soller, D.R., Berg, T.M., and Wahl, Ron, 2000, Developing the National Geologic Map Database, Phase 3 -- an online, "Living" database of map information, in Soller, D.R., ed., Digital Mapping Techniques '00 -- Workshop Proceedings: U.S. Geological Survey Open-File Report 00-325, p. 49-52, https://pubs.usgs.gov/openfile/of00-325/soller4.html.

Soller, D.R., Duncan, Ian, Ellis, Gene, Giglierano, Jim, and Hess, Ron, 1999, Proposed guidelines for inclusion of digital map products in the National Geologic Map Database, in Soller, D.R., ed., Digital Mapping Techniques '99 -- Workshop Proceedings: U.S. Geological Survey Open-File Report 99-386, p. 35-38, https://pubs.usgs.gov/openfile/of99-386/soller2.html.

Soller, D.R., and Lindquist, Taryn, 2000, Development and public review of the draft "Digital Cartographic Standard for Geologic Map Symbolization," in Soller, D.R., ed., Digital Mapping Techniques '00 -- Workshop Proceedings: U.S. Geological Survey Open-File Report 00-325, p. 43-47, https://pubs.usgs.gov/openfile/of00-325/soller3.html.

Soller, D.R., Wahl, Ron, Weisenfluh, Jerry, Brodaric, Boyan, Hastings, Jordan, Laudati, Robert, and Fredericks, Roger, 2001, Progress report on the National Geologic Map Database, Phase 3: an online database of map information, in Soller, D.R., ed., Digital Mapping Techniques '01 -- Workshop Proceedings: U.S. Geological Survey Open-File Report 01-223, p. 71-78, https://pubs.usgs.gov/of/2001/of01-223/soller2.html.

Wahl, R.R., Soller, D.R., and Yeldell, Steven, 2000, Prototype implementation of the NADMSC Draft Standard Data Model, Greater Yellowstone area, in Soller, D.R., ed., Digital Mapping Techniques '00 -- Workshop Proceedings: U.S. Geological Survey Open-File Report 00-325, p. 57-63, https://pubs.usgs.gov/openfile/of00-325/wahl.html.

Wardlaw, B.R., Stamm, N.R., and Soller, D.R., 2001, The U.S. Geological Survey National Paleontological Database, in Soller, D.R., ed., Digital Mapping Techniques '01 -- Workshop Proceedings: U.S. Geological Survey Open-File Report 01-223, p. 59-70, https://pubs.usgs.gov/of/2001/of01-223/wardlaw.html.

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