Hi all,

First of all, I am sorry for my noob question, I tried to google the answer, but it looks like the answer is so obvious (for everyone except me, haha) that nobody discuss this question.

On many exchanges I see the following logic of work:

- There are two Order Books: Buy and Sell
- There are two Order Forms (to create order): Buy and Sell
- If I click on the already created order from the Sell Order Book, it will auto fill the fields in the Buy Order Form.
- If I click on the  already created order from the Buy Order Book, it will auto fill the fields in the Sell Order Form.

The question is what for do exchanges need it? What is the logic behind it?

Because, as far as I understand, even after I "autofill" the form, and click Buy (or Sell), the matching will not be toward the order price (that I filled) but for the best price? Or no? Or it will match toward price I filled and all the better prices, and therefore there will be more than one matching and several buys/ sells?

Please, help.