Issued Appointment Letters Has Some Mistakes - Please Advice

Hi,
As far as I know the terms & conditions of the company changes as & when required but with proper working.
Suppose someone joined 10yrs back will have old terms & conditions .So whenever changes are made either a letter stating the amendment in particular cakuse of terms & conditions is issued and copy of same with employee signature is kept in his file.
Your HR mannual should state that the rules & regulations may change from time to time as per managment decision however the same shall be intimated to emplyee in time.
Regds
Pritha

Dear All,
I recently joined a new co.and they given me the task to issued the appointment letters to old employess. The problem is that i didnt know wheather i hv to issued letters or not. Pls give me reply asap.
Regards
Riya