FromPos[in] Position where the substring is started. Must be not less than 0 and not greater than the length of paragraph.ToPos[in] Position where the substring is ended. Must be not less than variable FromPos and 0 and not greater than the length of paragraph.String[out, retval] A pointer to BSTR variable that receives the substring that is started at FromPos position and is ended to ToPos position. Must not be NULL.