Standard output types for the DITA Open Toolkit are controlled by the plugins distributed with each version of the DITA-OT.
See the DITA-OT version of interest for information about the supplied plugins. http://www.dita-ot.org/.
Your system may be customized to add additional output types by importing a plugin folder for a new transtype. See Importing a Plugin Folder into a DITA-OT Folder.
When you issue the Compose with DITA-OT command, you must select an available DITA-OT version from those present in the repository, then select one or more output types supported by that version to compose.
If desired, an application administrator can revise the display names of the output types and also remove unwanted output types. See Renaming and Hiding Output Types for more information.