Employee grouping & E Sub grouping

HI

Could you please guide me in my client they have 3 levels like top mgnt , , middle mgnt , jr mgnt in this all three levels again divided to some grades

top mgnt - a1 vp

a2 Sr vp

middle mgnt - a3 AGM

a4 Deputy AGM

Jr Mgnt -

a5 - MGR

Can i take employee group as T for top mgnt employee sub group as a1 is it correct ? if not can you suggest me to divide the Employee groups & Employeee sub groups

Regards

RBS