I agree with the view of members that it is not mandatory. However, we should think of future requirements of the organizations, corporate branches, subsidiaries, sister concerns, overseas branches, transfers between locations, and interdepartmental transfers. Hence, we need to take care of these aspects and add a prefix code to the employee. This will help in resolving issues over decades.
If the employee code is not less than 6 digits, it would be sufficient for 2 to 5 decades. Also, we should consider the Types of Employees the company engages with, such as permanent, temporary, on contract, on loan, part-time, full-time, and also levels from 1 to 20 or 30.
I hope this sufficiently takes care of the concerns.