balance in formula

a problem about standard formula shipped with the system

formula name :CN_TAX_CALCULATION

code section:
  /* Common Balances */
  DEFAULT FOR PHF_SI_EARNINGS_ASG_PTD     IS 0
  DEFAULT FOR PHF_SI_EARNINGS_ASG_PYEAR   IS 0
  DEFAULT FOR PHF_SI_EARNINGS_ASG_PMTH    IS 0
  DEFAULT FOR TAXABLE_EARNINGS_ASG_ER_PTD IS 0

it seems that the above are balances, but i can't find the definition in the balance define

window, i query the definition in the way %PHF_SI_EARNINGS%.

also,it can't be found in table pay_balance_types_tl , sql as below:
select * from pay_balance_types_tl where balance_name like '%PHF_SI_EARNINGS%'