though this is company specific, the general rule followed is:
Basic Pay (Base pay + employers contributions towards retirals: PF, Gratuity, Superannuation Fund) +
Allowances (all cash allowances like Housing, Medical, Conveyance, Education, etc.)+
Performance Pay (fixed or variable bonus, estimated value of ESOP)+
Any other cashable benefit (mobile phones, fuel charges, food coupons, etc.)
hope this would help..
Cheers,
Sanjeeb