In order to guarantee a match of the most recently announced edition to the previously announced edition, you will need to purchase your copy during the Matching Pre-Order window.
If however, you wait for the public pre-order, provided you are an owner of record for the previously announced book, then we will still match your number automatically. You also do not need to know what your number is. Simply place the order (preferably using the same email address you used on your previous purchase), and we will match. It goes without saying that if you wait too long, and the book sells out, then we cannot match anything, because there is no book to match to.
One exception to this rule is that if an edition remains in stock for some time, and you wait too long to place an order, there is a chance that we have already assigned your number to someone else.
If you ordered during the Matching Pre-Order period and have purchased each book sequentially, your designation is guaranteed and will not change. However, for orders placed after the Matching Pre-Order window, designations may change after you place your order. If you check your designation using our Designation Search tool and later notice it has changed, this is working as intended. Our system continuously optimizes number assignments until designations are finalized and locked. Check your final designation closer to the publication date for accuracy.