DITA authoring has a number of peculiarities as DITA documents differ significantly from documents of other document types.
Referencing is an effective means of content reuse in DITA. Content reuse is available at different levels (elements, topics, maps) by means of different types of references.
Serna validates references.
In DITA, the uniqueness of ID attributes within a specific scope is essential for making references.
DITA IDs are ID attributes of non-topic elements. Unlike IDs of topic elements, which must be unique within the scope of the whole document, DITA IDs must be unique within the scope of the parent topic or map. DITA IDs are specially treated in Serna.
When you work with DITA documents, Serna maintains the uniqueness of DITA elements' IDs and reports duplicate DITA IDs.