What are the points to be covered by a letter containing an order?

When a company places an order the following points are to be covered:

1)      The quality of the goods required.

2)      The quantity of goods needed should be made clear.

3)      The type of packing required.

4)      The price and mode of payment.

5)      The time and place of delivery should be made very clear.

6)      Insurance of the goods during transit.

7)      The mode of transportation should be clear.

8)      The right to reject the goods on account of a defect in quality or delay in the delivery.

While it is not exactly a contract, it has a legal significance in the sense that a buyer cannot hold a seller responsible for not doing something which is not clearly mentioned in the letter containing the order. In the same way the seller cannot accept the buyer to pay more or accept goods different from those mentioned in the order.