Coding PML: a Question

Please, people I am confuse, I am writing a program for FDTD and I need o terminate the computational space with PML but I don't know if to use the normal descritized maxwell equation or the descritization for PML in Berenger's paper for both the computational space and the lattice truncation space(i.e the Boundary lattice for PML wall).I need an explanation urgently.

Thanks

I think you will write the equation of the descritization for PML in Berenger's paper for both the computational space and the lattice truncation space as the coefficients in the equation will be one in the structure computational domain and the equation reduce to the normal Maxuel equations but it will have values in the PML regions