DITA_OT_DIR

DITA_OT_DIR is the default directory that is specified for your DITA Open Toolkit distribution in the Options > Preferences > DITA preferences page.

For example, if you are using DITA 1.8, the default DITA OT directory is: [OXYGEN_INSTALL_DIR]/frameworks/dita/DITA-OT (or if you are using DITA 2.x, [OXYGEN_INSTALL_DIR]/frameworks/dita/DITA-OT2.x). You can also specify a custom directory.