Oxygen XML Editor allows you to select a DITA map as a key space, or root map, for all the other DITA maps and topics in the project. Specifying the correct root map helps to prevent validation problems when you work with keyrefs and also acts as the foundation for content completion. All the keys that are defined in a root map are available in the maps that the root map contains.
There are several ways to select or change the root map:
- The easiest method is to use the Root map drop-down menu in the DITA Maps Manager toolbar to select the appropriate root map.
- If you insert a key reference using the Cross Reference
action from the
Link drop-down
menu (from the toolbar or Link submenu of the contextual menu) and
keys are not gathered from the expected DITA map, you can change the root map by using
the Change Root Map link in the Choose Key
dialog box that is opened when you click the 
Choose Key Reference button. - If you insert a content key reference or key reference using the
Reuse Content action (from
the toolbar, DITA menu, or Reuse submenu of
the contextual menu) and keys are not gathered from the expected DITA map, you can change
the root map by using the Change Root Map link in the
Choose Key dialog box that is opened when you click the
Choose Key Reference
button.
To watch our video demonstration about the DITA Root Map support, go to http://oxygenxml.com/demo/DITA_Root_Map.html.