DITA

DITA is an XML standard for documentation and processing from OASIS. It shares some of the same architectural concepts as PageSeeder.

These include:

• Specialization – DITA is designed so that it can be extended without requiring any substantial changes to the software. (see PSML and document template).
• Topics – designed to be self-contained document objects assembled by maps. (see document type).
• Maps – binders that organize topics for processing. (see references document type).
• Keys – identifiers that can be used for linking and other operations. (see Doc ID or URI ID).

DITA also uses a two-stage processing architecture to, firstly, resolve the linked objects into the correct order and hierarchy, and secondly, to transform the XML into a formatting language. 

A PageSeeder tutorial explains some of the support available for LightweightDITA or LwDITA.