ZX_RATES_B as a replacement for AP_TAX_CODES_ALL

Hi,

     I am associated with a migration project from 11i to R12 .

In one of the reports that I am migrating AP_TAX_CODES_ALL table is used and a join is made with the gl_code_combinations table in the following statement

gcc.code_combination_id(+) = c.tax_code_combination_id

c-->AP_TAX_CODES_ALL

gcc-->gl_code_combinations

I replaced ap_Tax_codes with zx_rates_b but there is no tax_code_combination column in ZX_RATES_B.

I want to know which column to use inplace of this column.

Any help is this regards will he highly helpful.