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# Spatial Data Transfer Standard (SDTS)

### Fact Sheet 077-99 (May 1999)

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### Background

The American National Standards Institute's (ANSI) Spatial Data Transfer Standard (SDTS)is a mechanism for archiving and transferring of spatial data (including metadata) betweendissimilar computer systems.  The SDTS specifies exchange constructs, such as format, structure,and content, for spatially referenced vector and raster (including gridded) data.

The SDTS includes a flexible conceptual model, specifications for a quality report, transfermodule specifications, data dictionary specifications, and definitions of spatial features andattributes.

### Advantages

Advantages of the SDTS include data and cost sharing, flexibility, and improved qualityinformation and metadata, all with the potential for no loss of information during transfer.  TheSDTS is not vendor specific or proprietary.

### Status

The SDTS was approved as ANSI/NCITS 320.1998 in June 1998. The ANSI standardcovers the base standard (SDTS Parts 1 through 3) and the (SDTS Part 4) Topological Vector Profile(TVP), the first profile designed for a specific type of data.

Use of the SDTS became mandatory for Federal agencies in June 1994.  At that time, Part 4of the SDTS standard was added to FIPS 173, and the name was changed to FIPS 173-1. 

The SDTS serves as the spatial data transfer mechanism for all federal agencies and isavailable for use by State and local governments, the private sector, and research and academicorganizations.

Part 5, Raster Profile with Extensions (RPE), was approved by the Federal Geographic DataCommittee (FGDC) as an FGDC standard.  Part 6, Point Profile, was approved as an FGDCstandard in 1997.

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Implementation Support
The U.S. Geological Survey (USGS) remains the designated maintenance authority for thebase standard and SDTS Parts 4 (TVP) and 5 (RPE).  Maintenance of other profiles will be conducted by the sponsoring organization(s).  The Point Profile (SDTS Part 6) ismaintained by NOAA, the agency that developed and championed it through the FGDC approvalprocess. 

As the primary maintenance authority, the USGS is committed to increasing the acceptanceand use of SDTS as follows:

Profile development—A profile is a clearly defined and limited subset of the SDTS,designed for use with a specific type of data.  The most effective way to use the SDTS is to first define aprofile; encoding and decoding software can then be designed to handle only the options in theprofile.  The USGS will continue to provide technical guidance to organizations wishing todesign, implement, and maintain additional SDTS profiles.

Consumer Support—The SDTS Task Force located at Mid-Continent Mapping Centerprovides a point of contact and a source of information about SDTS issues and data.  The task forceprovides SDTS consumer support in the form of literature, online information, and participationin workshops, seminars, and presentations at events on national and international levels.  To getassistance, send e-mail to [email protected].

GIS Software Vendor Support—The SDTS Task Force actively supports efforts bysoftware vendors to add to or enhance existing SDTS capabilities in their software packages.  The taskforce provides technical guidance and beta testing for selected software packages. Someconsumers prefer to use less expensive GIS software that has comparatively less functionality,and some prefer to use packages with the greatest functionality, regardless of the cost.  For thesereasons, support is given to vendors at all levels of the function and cost spectrum.

Public Domain Software—The USGS offers dlgv32 software for viewing SDTS dataand SDTS support software for programmers at  mcmcweb.er.usgs.gov/sdts/public_domain.html.  This site also includes the FIPS 123 function library with source codeand Master Data Dictionary (MDD) software to create MDD transfers from ASCII input files.

User Guides—Because of the complexity of the SDTS, and to promote education, theUSGSdistributes articles, a list of frequently asked questions (FAQ), user guides, and training materialthrough the SDTS Web page. 

Conformance Testing—Conformance tests capture the technical description of theSDTS andmeasure whether or not a product faithfully implements it.  Faithful implementation of thestandard makes it possible for consumers using different software packages and data sets fromdifferent data producers to get the same consistent results.  Detailed information about SDTSconformance testing is available on the SDTS Web page.

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Data Availability
The US GeoData page, maintained by the EROS Data Center, contains down-loadable data,information, and public domain software that is currently available at no cost to the consumer.Available data include 7.5-Minute Digital Elevation Models (1:24,000-scale), 1:2,000,000-scaleDigital Line Graphs, and Large Scale Digital Line Graphs (1:24,000-scale).  Geodata downloadstatistics available through this page reflect the growing use and acceptance of SDTS data by theGIS community.  To visit this site, go to edc.usgs.gov/geodata/.
Online Information
The SDTS (FIPS 173-1, all parts) and related documentation are available in electronic formthrough anonymous FTP on the Internet at the following address:

ftp://sdts.er.usgs.gov/pub/sdtsUser: anonymousPassword: your e-mail addressAfter connecting: cd pub/sdts
The OOREADME file contains information on the contents of each subdirectory.

The SDTS Web page contains a wealth of information with links to other items of interest toconsumers, standards organizations, programmers, and potential developers of additional SDTSprofiles.  The SDTS home page can be found on the World Wide Web at mcmcweb.er.usgs.gov/sdts.
Sites to Visit SDTS Web page: mcmcweb.er.usgs.gov/sdtsUS GeoData page:  mcmcweb.er.usgs.gov/sdts/public_domain.htmlSDTS FTP site:  ftp://sdts.er.usgs.gov/pub/sdts National Mapping Program Geospatial Standards:geography.usgs.gov/standardsFor More Information
For additional information about the SDTS or how to participate in related developmentactivities, contact:

U.S. Geological SurveyAttn:  SDTS Task Force, MS 5081400 Independence RoadRolla,  MO   65401-2602E-mail: [email protected]573-308-3561

Paper copies of the SDTS are for sale from:

National Technical Information ServiceComputer Products Office5285 Port Royal RoadSpringfield, VA   22161703-487-4600

Request FIPSPUB 173-1a for parts 1, 2, and 3 of the standard; and FIPSPUB 173-1b for part4.

For information on these and other USGS products and services, call 1-888-ASK-USGS,  or visit the general interest publications Web site on mapping, geography, and related topics at erg.usgs.gov/isb/pubs/pubslists/.

For additional information, visit the ask.usgs.gov Web siteor the USGS home page at www.usgs.gov.

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*Any use of trade, product, or firm names is for descriptive purposes only and does not implyendorsement by the U.S. Government.This document has undergone official review and approval for publications established by theNational Mapping Division, U.S. Geological Survey. Some figures, have been modified or addedto improve the scientific visualization of information.*

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