How to specify the generated code in initialization section with Mathworks embedded coder?

In auto code using 2011a, it always inserts some "custom signals" in initialization secion such as x1 = ((uint16_T)0U); x2 = ((uint16_T)0U); x3 = ((uint16_T)0U);

as shown below. I 'm not sure how this part code is generated and how to specify the code generated for "custom signals" if I need.

Thanks, Yixin

void Example_initialize(void) { /* Registration code */

/* block I/O */

/* custom signals */
x1 = ((uint16_T)0U);
x2 = ((uint16_T)0U);
x3 = ((uint16_T)0U);
...
}