Index of a data type work vector, where the index is one of 0, 1, 2, ...ssGetNumDWork(S)-1.
A pointer (void *) to the DWork vector specified
by the index vector.
Use to obtain a pointer to a particular DWork vector. See How to Use DWork Vectors for more information
on DWork vectors.
Do not use any of the SimStruct functions
that get information about DWork vector if your S-function does not
contain any DWork vectors. Otherwise, your S-function produces errors