Do business customers understand ACH terminology? When allowing them to block unauthorized ACH transactions or only grant access to authorized transactions, how to business cutomers refer to these? Please provide me a good site if you know one. Thank you!

Not very often. Go to NACHA.org and order an ACH Rule book..it's indispensible.

Well, I'm a banker, and am a bit confused by your question. For one, how would a customer know in advance to block an unauthorized transaction? You don't know about it until it hits your account, hence the term unauthorized. As far as granting only authorized transactions, I'm not aware of any bank that requires customers to tell them in advance what debits to accept.

As far as terms "unauthorized," "debit," "transaction," I think that 99.99% of business customers understand these.

Perhaps if you could better clarify what issue you are having with the customer?