documentation for OFX import

[Risto Paasila]

I have tried to find documentation on OFX import in the wiki,  
concepts guide and the help manual, but there doesn't seem to be any.
In particular I want to know whether importing bank transactions  
using OFX is supposed to go against invoices. I have gnucash 2.0.5.

I have set up invoices for customers, which appear in the account  
receivables account,
so when they have paid, the imported transaction should automatically  
go against the invoice,
so that the payment should show up in the customer report.

Thank you.
Risto