Collection constraints function much like document sets, and are ideal for use in B2B environments, where catalog-based document sets can be numerous enough to slow searching. Collections do not include hierarchies and cannot be browsed, but are a simple switch that indicates whether a given document is part of the collection.

<collection>/Meta/name/value</collection>

In order to use collection constraints, index your meta-property with store-as-collection=true in the IndexingOutputConfig component.