DITA_OT_DIR
DITA_OT_DIR is the default directory that is specified for your DITA Open
Toolkit distribution in the preferences page.
For example, if you are using DITA OT 2.3.3, [OXYGEN_INSTALL_DIR]/frameworks/dita/DITA-OT2.x
(or if you are using DITA OT 1.8.5, the default DITA OT
directory is: [OXYGEN_INSTALL_DIR]/frameworks/dita/DITA-OT). You can also specify a custom directory.