MKL from C

I am having trouble understanding C interface for MKL. In particular the const modifier. I need to use tridiagonal solver ?dtsvb which should have C interface:

void ddtsvb (const MKL_INT * n, const MKL_INT * nrhs, double * dl, double * d, const double * du, double * b, const MKL_INT * ldb, MKL_INT * info );

However, I have no idea what const MKL_INT * n stands for. Can someone provide a clear example of how the function ddtsvb is called?

Thank you.