DITA map processing Introduction to this chapter to be written later, when content is more stable. DITA maps and their usageNew topic cluster to hold normative architectural content about DITA maps. Currently holds notes about material that we intend to cover in the new topic cluster.Subject scheme maps and their usageSubject scheme maps can be used to define controlled values and subject definitions. The controlled values can be bound to attributes, as well as element and attribute pairs. The subject definitions can contain metadata and provide links to more detailed information; they can be used to classify content and provide semantics that can be used in taxonomies and ontologies.Metadata cascadingMetadata cascading is the process by which metadata elements and attributes specified for a map or for a topic reference cascade to nested references. This allows metadata properties to be set once and apply to an entire map or branch of a map.ChunkingContent often needs to be delivered in a different granularity than it is authored. The @chunk attribute enables map authors to specify that multiple source documents should be combined into a single document for delivery or that a single source document should be split into multiple documents for delivery.