David Hansen and Michael Sebhat

Reporting Metadata for Access in ArcView and across INTERNET within the ArcInfo Data Model

ABSTRACT: The Content Standards for Digital Geospatial Metadata when used as guide for the content of metadata can assist an organization providing key information for the use and managment of its GIS data sets. Our organization, MPGIS, identified metadata elements that are useful in accessing and applying our data sets. Additional metadata elements not in the standards, were required for the management of our data. This metadata serves as the basis for are on line catalog of GIS data sets and their status on the system. This metadata consists of text files in HTML format. Viewing tools such as MOSAIC or NETSCAPE with indexes of the metadata to access metadata for individual GIS data sets. These indexes are organized by our project accounts and by data set theme. The HTML documents can be moved as needed to our World Wide Web site for access over INTERNET.

A smaller set of these metadata elements is also produced to meet the needs of our ArcView users. This metadata besides identifying the data set and describing attribute information and associated tables, also identify the data set map units and the resolution of features with suggested display scales. Avenue scripts provide access to these descriptions as well as to the project and theme indexes. This permits the user to browse the metadata for other GIS data sets for the same project or by theme with MOSAIC or NETSCAPE.

The metadata in these text files only represents a subset of the information needed for the transfer of GIS data sets. When a data set is ready for transfer, the existing metadata files are reviewed. A file containing lineage information is prepared and updated. This information along with a file describing MPGIS compliance to the standards completes the metadata description. This file on compliance identifies the metadata elements described and the terms used by MPGIS that are not in the standards. Metadata elements that are not addressed in the metadata description are identified and explained.


This paper concerns the implementation of the Content Standards for Digital Geospatial MetaData for the use and benefit of the organization. The costs in preparing and maintaining metadata have usually not been considered in the development of data sets including geospatial data sets. These costs include delays in providing requested information while the required metadata is prepared and reviewed. There are also benefits to the organization. The Content Standards identify reduced cost in avoiding the duplication of existing digital data sets. The E.S.R.I. White Paper on Metadata Management in GIS identifies benefits accruing to the full integration of metadata into the information base of the organization. It is clear that the development of metadata in any organization will always be a problem where the benefits of full access and use of metadata within the organization do not clearly exceed the costs in developing and maintaining metadata.

Metadata should be viewed as a component of the GIS data set that provides information supporting the use and application of the data set. As a dynamic component, it can be used internally by the organization as well as support the transfer of the spatial data to others. To illustrate this, the integration of metadata into our organization, MPGIS, will be described.

This paper represents the further development of concepts presented in a paper by Hansen and Sebhat at the 1995 E.S.R.I. User Conference. This previous paper focused on sections of the standards and the incoporation of that information into text file format. This paper focuses on the development of metadata to meet the needs of our organization for use as:

The Content Standards are used as a guide to identify and label information for the management of our GIS data sets. Some of the information required for management of the spatial data are not currently part of the Content Standards .

Metadata Management Requirements for MPGIS

The basic organizational unit for MPGIS is the project. The cost accounting system is set up by project. It determines why a data set is captured and who is responsible for the data set. The computer system directories are organized by project. A project identifier is a key piece of metadata for all GIS data sets held by MPGIS. Therefore, metadata prepared by MPGIS is organized in files by project.

A secondary unit of organization used by MPGIS is the data base theme. Data base theme is used as a cross index to similar data sets that are under separate project accounts. It assists in identifying similar GIS data sets that may have additional information or improved spatial resolution that cross project boundaries. A review of themes also provide users the opportunity to browse similar data sets that may be useful for their applications. It assists in maintaining consistency in the structure and description of data sets of the same theme.

The project identifier and the theme act as the key items for accessing MPGIS data sets and metadata. They cross reference the MPGIS text files of metadata. These text files provide the following information about the data sets.

This information and lineage information on the development of the GIS data set serve as the basis for metadata management of our GIS data sets. They also serve as the on-line metadata for the system.

Metadata as an On-Line Catalog of Available Digital Geospatial Data Sets

The components of the catalog of GIS data sets are HTML documents that can be viewed with a viewer such as MOSAIC or NETSCAPE. These HTML documents are stored under an overall metadata directory which has subdirectories corresponding to individual projects. These separate files are linked to an overall index of projects and a cross index of themes. The project index or theme index leads to separate HTML documents for each data set. This catalog is immediately available with an HTML viewer for access on the system. Metadata for data sets which are complete and appropriate for release can be made available for access over INTERNET as HTML documents.

View of an INDEX for a Project and a GIS
description in MOSAIC

Image of the MetaData index and a data set description in MOSAIC

Metadata as an On-Line Description of GIS Data Sets for Access in ArcView

With the development of ArcView, MPGIS has many new users on the MPGIS system. These users need information that: This information represents a subset of information in the HTML files written for the catalog. At the time that the HTML files are prepared, a simple file providing this information is written. In ArcView, these text files are accessible to the user with Avenue scripts. These scripts use an independent table that links GIS data sets to the text files of metadata. ArcView menu options display the text file for any selected theme. This metadata provides a brief description of the GIS data set and the associated table attributes. It identifies the project and theme.

View of the presentation of metadata
Information in
ArcView with metadata Avenue Application

Image of the MetaData information in ArcView for a theme

The text file provides information for setting the map units of the view. Minimum and maximum display scales for individual themes are also suggested. It provides an estimate of resolution of features which can be useful in developing the view. Avenue scripts provide an opportunity for automatically setting view map units, maximum, and minimum display scales based on the themes that are loaded.

Menu options provide the opportunity for searching the online catalog of other GIS data based on project or theme. Scripts start up the HTML viewer to access the project index or the theme index.

View of Menu options for accessing the
project index
or theme index of HTML files in a ArcView Application

Image of an ArcView application accessing the system project index via the ArcView menu

Metadata as a Management Tool for digital Geospatial Information Base

The management of the GIS system is assisted by access to the information contained in these files. These files identify currently active GIS data sets and those data sets that have been archived to tape. Descriptions of the data sets, associated tables, source scale, final disposition, and digital capture procedure provide sufficient information for the review and management of many of the GIS data sets.

Some data sets are inherently more complex. Some require extensive coordinate or feature adjustment to match the project base data set. Some have been updated because of changes in the spatial or attribute components or both. More accurate coordinate information may have become available. Changes may have occurred in the representation of the spatial features such as boundary changes, construction of a road, or addition of sampling locations, etc. The attributes may represent periodic reporting of sampling data. All represent changes over time with the development of a complex history. This history represents the data set lineage. Data set lineage provides the basis for assessing the quality of a data set for an application.

The lineage describes the sources used in modifying a spatial data set and should identify the features that were modified. The initial step is identifying the initial source data set, coordinate transformations, and adjustments. As the data set is further modified, the lineage report needs to be reviewed and updated. Part of this information is available in ArcInfo or in the system log files. MPGIS describes the lineage of a data set in a separate file which is stored with the other metadata files.

Metadata to Accompany the Transfer of GIS Data Sets

The Content Standards identify the documentation required for GIS data set transfer. The element names identified in the standards are used with unique tag names in preparing the information provided in the metadata files.

A complete metadata description is not prepared at one time but only as appropriate. The first major components are those prepared for the on-line data catalog. Major sets of elements in the Content Standards covered in these files are the following:

Only the identification information section is entirely complete. The other files are reviewed and finalized when the GIS data set is ready for transfer. If a lineage file does not exist, one is generated.

Compliance with the FGDC Content Standards for Digital Geospatial Metadata

Metadata required in data transfer is more comprehensive than that developed by MPGIS for on-line catalogs or for data management. Some of this information is required for a successful data transfer where the transfer involves other software or hardware systems. Some is required to document the terms used and the authorities for those terms. Much of this and other information is the same for all data sets held by an organization. Duplicating this information in the metadata for a data set can add substantially to the size of the data set without providing much additional useful information.

For MPGIS, this is handled by an overall file of the FGDC metadata elements. Elements which are addressed in the MPGIS metadata are identified. Their location in the prepared files, type, and domain are given. Elements which are system dependent or which are common to all MPGIS data sets are described in this file. Elements which are not addressed by MPGIS are identified and explained. Terms which are not contained as elements in the FGDC standards but which are used in MPGIS metadata are identified and defined. This file acts as a statement of compliance with the Content Standards for Digital Geospatial Metadata . It can also serve as a lookup table for use when data transfer occurs or when the standards are modified.


MPGIS uses metadata as a tool to provide access to our GIS data sets and manage those data sets. Elements as described in the Content Standards for Digital Geospatial Metadata are used where ever possible in these descriptions. Only those elements which are directly applicable to the management of the data are described for individual GIS data sets. Additional terms not contained in this standard are used where they are required to manage the GIS data sets. A compliance file identifies the elements that are described in these files and those that are not. It defines the use of terms or elements which are not contained in the standard.

Metadata for the GIS data sets are prepared as HTML documents for use with an HTML viewer or as text files for use in ArcView with Avenue scripts. Indexes are set up based on MPGIS projects and data set themes. The indexes link the HTML metadata documents for use both on the system and for access via INTERNET. These interim metadata files serve as the basis for preparing metadata for GIS data transfer. Metadata for a GIS data set is only considered to be complete when the data set lineage has been prepared and reviewed and the data set is ready for transfer.

The Content Standards for Digital Geospatial Metadata is used as a guide in the development of these data set descriptions. It provides the names and definitions for most elements used. The metadata prepared by MPGIS is based on:

  1. The uses of GIS data in the organization.
  2. The people in the organization that access the GIS system and the information that they need to properly use the spatial data.
  3. The information needed to respond to requests for spatial data.
  4. The information needed to manage the data sets both on line and in archive.
  5. The types of spatial and data base analysis that are done.

Current and Future Developments in Metadata

E.S.R.I. besides providing DOCUMENT.AML as a metadata managment tool is also in the conceptual stage of developing a metadata manager. This manager would share metadata between ArcInfo and ArcView. The manager is briefly outlined in the white paper Metadata Managment in GIS .

A Dublin CORE group is in the process of identifying key elements for indexing of digital documents including geospatial data. Such an index would act as a bibliographic listing. It would assist in performing queries against data bases constructed with the core elements. An ISO (International Standards Organization) is beginning to prepare standards on metadata. The current FGDC standards are under review for modification and further extension.


Department of Commerce. Spatial Data Transfer Standard . National Institute of Standards and Technology, FIPS 173. Washington, D.C. 1992

E.S.R.I. Metadata Management in GIS .:Esri White Paper Series. Redlands, CA, August, 1995.

FGDC. Content Standards for Digital Geospatial Metadata . Washington, D.C. June 8, 1994.

Hansen, David and Michael Sebhat. Compilation of Spatial Metadata for Access in ArcView and Mosaic . Paper presented at the 1995 E.S.R.I. User Conference. Palm Springs, CA May, 1995

David Hansen
GIS Specialist
Michael Sebhat
GIS System Administrator
U.S. Bureau of Reclamation
2800 Cottage Way
Sacramento, CA 95825-1898
Telephone:(916) 979-2418
Fax: (916) 979-2505
Email: dhansen@mpgis7.mp.usbr.gov
Email: msebhat@mpgis1.mp.usbr.gov