PCR for Voluntary income tax

Hi gurus,

I found a PCR in one of my implementation for calculating voluntary income tax for india payroll.

Few lines of pcr appears as given below:

ZTAX

    *

      91TX

         AMT?10

           =

               ELIMI *

               AMT=0

               AMT -S /460

               ADDWT /460

               AMT=*

               AMT -S /4MT

               ADDWT /4MT

               ---

               --

I want to know, what is the meaning of ADDWT -S /4MT. I am understanding the balance lines.

Please throw some light on this.

thanking you.

regards,

Raj.