DOV (Default Output Value) is present only in bitstreams made with RT-XSG v3.2.6 or later. See also RT-XSG Documentation.
This feature makes it possible to control the behavior of the output signals during PAUSE or RESET states. Values and behaviors are chosen before generating the bitstream and are not user-modifiable afterward.
DOV is supported regardless of the Driver (S-Function, OPALBOARD, or HYPERSIM).