Is there a 'PO Header Note exists' flag?

I have to display the PO header note in my report.

I do know how it works with FM READ_TEXT.

For Network RESB-LTXSP indicates if there is a long text.

My question is that if there a similar flag for 'PO Header note exists'?

For performance reason it would be good to call FM READ_TEXT only for POs where there is header note.

Thanks in advance,

Incho