Employee code - is there any standard format or way that should be considered while creating them?

Dear All, I am working in an audit firm, we are planing to buy an HR Software for which we need to generate the employee codes, is there any standard format or way that should be considered while creating the employee codes, also we have trainees who undergo an articleship training for 3 years, should they also be given a code ? or the codes for these trainees should be generated separately?

You can generate any code number of your choice. While creating code number you can check with the firm/company from where you would like to instal HRMS software and seek their opinion.
You can even start a number with, say 'A00001', like that.
The only thing you have to bear in mind that, if an employee with a particular code no leaves the
employment, the code number allotted to him also dies. Do not allot the same code number to any new employee.
It is proper that code number for trainees shall be generated separately.