Question on DS-156

I have a question regarding item #20 on DS-156, name and address of the present employer:

My parents are both retired. Should they put down their former employer's name and address or leave it as "NA - retired".

My parents said someone at CITIC providing consultation told him that he should for sure to enter his former employer name under #20. But when I asked the question here sometime ago, I was told we should put down "NA - retired."

Can someone please let me know what is the best thing to do for item #20?

Thanks much!