The Appointment Letter will be same as the personnel deployed under payroll for client establishment/location/s. Bcoz primarily they are your employees. However, in order to identify instantly you can start mentioning some code before their “Employee ID No.”. Moreover, in the Appointment Letter you can mention the location/establishment name. But same need to be change (if the employee is being transferred to other client / location, which generally not happens).
If you have some regional branches, the ID can be generated on basis of State/Region. The ID in r/o direct employee (your staff) may be given as HO-======.
Hope this will serve your purpose. Fellow members can put more light on the matter.
10th May 2017 From India, Delhi