As described in the refineConfig section, Oracle ATG Web Commerce Search can calculate refinements based on the query results, in order to offer the end-user a quick way of narrowing the search.

The prop value is the name of a property to use for automatically selecting a refinement configuration based on the search results. This value must be accompanied by a refineConfig value of $map.

<query refineConfig="$map" refineConfigDefault="default"
refineConfigMapProp="ancestorCategories.repositoryId"
refineConfigMapKey="cat1009"