In the DITA standard architecture you create documents by collecting topics into maps.
A DITA map organizes a set of topics into a hierarchy. In most output formats, the structure of the map becomes the structure of the table of contents. Oxygen XML Editor provides support for creating and managing DITA maps through the DITA Maps Manager. There are also specialized types of DITA maps, such as a book map, which is intended for creating the structure of a book.
You do not have to create an entire publication using a single map. It is generally good practice to break up a large publication into several smaller sub-maps that are easier to manage. You can reuse sub-maps in a variety of different publications by including them in each of the main maps. The DITA Maps Manager provides support for easily creating and managing sub-maps.
By default, many output types place a single topic on each output page. In some cases you may want to output multiple topics as a single output page (also known as chunking). To support this, Oxygen XML Editor provides an Edit Properties dialog box that allows you to easily configure the attributes of a topic to control how your table of contents and topics are rendered in the output.
To watch a video on DITA editing , go to http://oxygenxml.com/demo/DITA_Editing.html.