direction.xsd See ISO/DIS 19136 Clause 18. The direction schema components provide the GML Application Schema developer with a standard property element to describe direction, and associated objects that may be used to express orientation, direction, heading, bearing or other directional aspects of geographic features. GML is an OGC Standard. Copyright (c) 2007,2010 Open Geospatial Consortium. To obtain additional rights of use, visit http://www.opengeospatial.org/legal/ . The property gml:direction is intended as a pre-defined property expressing a direction to be assigned to features defined in a GML application schema. Direction vectors are specified by providing components of a vector. deprecated direction descriptions are specified by a compass point code, a keyword, a textual description or a reference to a description. A gml:compassPoint is specified by a simple enumeration. In addition, thre elements to contain text-based descriptions of direction are provided. If the direction is specified using a term from a list, gml:keyword should be used, and the list indicated using the value of the codeSpace attribute. if the direction is decribed in prose, gml:direction or gml:reference should be used, allowing the value to be included inline or by reference. These directions are necessarily approximate, giving direction with a precision of 22.5°. It is thus generally unnecessary to specify the reference frame, though this may be detailed in the definition of a GML application language.