I-485, question about A-number

[Andy0000]

Hello everyone,
I have a question about I-485 form. My wife, she is F-2 visa and doesn't have A-number. For I-485 form, should I just leave her A-number blank or?
I cannot find any instructions for this situation on USCIS website.

Thanks for your helping.

[Turk]

I-485 asks for "A-Number (if any)".

I have a current H-1B visa which doesn't have that. I had OPT EAD card before my H-1B which has the A-Number (USCIS #).

I couldn't find any documentation or statement on what I should fill in A-Number in my case. Anyone has...