A GML Object Collection is any GML Object with a property element in its content model whose content model is derived by extension from gml:AbstractMemberType.<br/>In addition, the complex type describing the content model of the GML Object Collection may also include a reference to the attribute group gml:AggregationAttributeGroup to provide additional information about the semantics of the object collection.  This information may be used by applications to group GML objects, and optionally to order and index them.<br/>The allowed values for the aggregationType attribute are defined by gml:AggregationType. See 8.4 of ISO/IEC 11404:1996 for the meaning of the values in the enumeration.<br/>