Con- tractual obligations are created and defined by objective signals the parties exchange. 183 Ill. App. 80 Ill. App. See UCC sec. 141 Ill. App.
Documents exchanged by the parties establish the terms of their agreement.
This leads us back to the invoices. GRC received more than 200 of them, and it does not plead ignorance of their contents. Silent acceptance of these invoices com- pleted the contract on their terms. GRC's initial reaction to the August 1989 demand for payment supplies an additional clue. GRC first quibbled with the calculation of the amount due and then claimed that the failure to pay for product could not by itself be a default under the escrow agreement.