How to do that (posting zero value invoice )

Hi,

In my sceneriu i need to create solution to post sales invoice with zero prices (invoice amount = 0 ).

I try to find way in FormLetterServiceControler and depend classes but I stil don’t have one clear idea how to do that.

Mayby somebody done something like that and can help me ?

What business requirement are you trying to implement by posting invoices without any amount?