Following are authoritative FGDC Content Standard for Digital Geospatial Metadata (CSDGM) XML schema document (XSD) and document type definition (DTD) URLs for FGDC-STD-001-1998. These documents are used to validate a FGDC XML metadata file.

• http://www.fgdc.gov/metadata/fgdc-std-001-1998.dtd - Usage:
  

  <?xml version="1.0" encoding="ISO-8859-1"?>
  <!DOCTYPE metadata SYSTEM "http://www.fgdc.gov/metadata/fgdc-std-001-1998.dtd">

• http://www.fgdc.gov/metadata/fgdc-std-001-1998.xsd - Usage:
  

  <metadata 
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
       xsi:noNamespaceSchemaLocation="http://www.fgdc.gov/metadata/fgdc-std-001-1998.xsd">

There are also annotated and modified FGDC-STD-001-1998 schema available for download: