A SPADE Product Definition Document is an XML document that provides all the necessary information about one or more products that are to be managed by a SPADE archive. A SPADE_Config document may contain one or more ProductDef elements as well as any number of ItemDef (non-product) definition elements. Contains product specifications. Defines a collection of information which may be a top-level product, or it may be a sub-component used in a collection or reused by other item definitions. Description of a "abstract" metadata field. An abstract field is a field that does not belong to any particular item - a common metadata field. Abstract field definitions do not specify their XPath which is item-dependent. The field may be an element or attribute. Description of a single metadata field that is to be harvested. A field may be an element or attribute. The harvested value is the text value of the field, either element text or attribute value. Currently, emtpy elements are not supported. Indicates that an index should be built on this field. Description of a single metadata field that is to be harvested. A field may be an element or attribute. The harvested value is the text value of the field, either element text or attribute value. Currently, emtpy elements are not supported. A CommonField is a field that is harvested into a common table for cross-product queries by common metadata. If the element contains a DbColumn element, then the field is also harvested into the item table. This item references another externally-defined FieldDef. Description of a collection of items that are to be harvested into their own table. Are items of this type required for the containing item to be valid. This attribute gives the local name for the referenced item. This attribute, in combination with the namespaceUri attribute, identifies the referenced item. The namespace of the referenced item.