Email confirmation including 'static' info

We're using Authorize.net and Pay By Check.

When a person purchases and pays they get a confirmation email that includes 'You have selected the 'pay-by-check' option' text - even if they paid by authorize.net.
The email text is appearing below the address area and it is including what appears to be some 'static' text - it has 'Please include the order number' followed by what appears to be the first order number we ever generated.

I'm thinking that possibly this is just something from some view template or something that got added manually. I've looked through all the view files that I've modified and can't find it anywhere.

Can anyone point me to any files that might have gotten manually updated to include this for all order confirmations?

[It would be VERY helpful to have a full list of all the view files that explains where each one is used.]

Nevermind ... found it.
The language file for ORDER_VALID_AFTER_PAYMENT got changed to include all that stuff.