GML 3.1.1 Schema Package Readme The schema package contained in this directory is the normative GML 3.1.1 schema set as approved by the OGC membership in May 2005. This version corrects a number of errors in the GML 3.1.0 schemas that prevented validation. Reason for Changes: The XML Schema for GML 3.1 fails to validate using several of the most popular XML processing software applications. Four sets of errors have been found in the GML 3.1 Schema, with corrections applied as described: 1. the content model for "metaDataProperty" is non-determinstic: you can't have a choice group containing with anything else - delete _MetaData from the choice group 2. membership of the _timeLength, _Value, _ScalarValue, _ScalarValueList substitution groups relies on an interpretation of the XML Schema specification which is not uniformly accepted - replace with an explicit groups 3. axisName (type="string") in grids.xsd clashes with axisName (different type) in coordinateSystems.xsd - Remove the latter, use the gml:name property instead 4. a "derivation-by-restriction" pattern used widely throughout the schema has a cardinality constraint (minOccurs="0", and sometimes maxOccurs="unbounded") applied to a "property" element in a base type, where the property element is the head of a substitution group; in a type derived by restriction in which one or more members of the substitution group is selected, the validation procedure described in the W3C XML Schema specification requires that the validation constraint appear on a container element, rather than on the substitution group member element - move the cardinality constraint up to the container element - remove unnecessary derivation-by-restriction chains, particularly concerning derivation of property elements As this pattern is used pervasively in GML, there are numerous changes in almost all of the schema documents. The revised schema has been tested with Xerces-J, XSV, .NET, MSXML and no validation errors are found. http://schemas.opengis.net/gml/3.1.1/ 2005-08-11