are there SKU numbers?

Are SKU numbers used in ZC?
As I enter products I am not seeing SKU numbers. Does ZC automatically insert these? Or is there a setting somewhere to turn this feature on and off?

You have to add it in yourself as an attribute that you set up.
There are some add-ons that are supposed to let you do it easier if you go to add-ons and search for the term attributes.

Attribute?
I thought that ended up being something (check box, etc) that the customer uses to further enhance their choices. Like what color do you want, what size?, ect. How can that help add a field in admin for adding SKU to a product?

Can I simply use the model number as a SKU?

When a customer purchases something, is the model number displayed on the order confirmation? My concern is that after a customer orders something, how am I going to know EXACTLY which item they ordered without a SKU number? I have descriptions but most are very close to the same. I include photos of each item to make it easier and quicker for the customer.

I don't know for all those questions except one - Yes model #s do show up on orders. I just ran through my last 50 order emails and they show up in parenthesis just before the price. So that would be an easy place to put it if you want it to show up on orders, but where would you put model # then?

There is this add-on which will give you space to put in a UPC:
http://www.zen-cart.com/index.php?main_page=product_contrib_info&products_id=651
You may be able to modify it to your needs too.

Nothing I have has a model number so I don't really need that for that purpose. I would rather use it for SKU number.

My main purpose is some kind of differentiating system so that when I get an email saying that an order has been placed, I know which item to send them, since my descriptions are very similar. In other words, I have about 15 different bonsai pots that are rectangular and green. Even if I put in the dimensions, I would have to measure every green pot I have to find the one they ordered. But the SKU (model number) once I know what it is, write it on the price tag that is on the item.

Well then putting the SKU in the model # field will work will work easy.

You can use this mod to add a SKU number field:

http://www.numinix.com/numinix-product-fields

RescoCCC:

You can use this mod to add a SKU number field:

http://www.numinix.com/numinix-product-fields

From reading the Numinix website, this mod is for adding product fields to NUMINIX modules, not to my existing ZC admin. Correct me if I am wrong.

FukienMan:

From reading the Numinix website, this mod is for adding product fields to NUMINIX modules, not to my existing ZC admin. Correct me if I am wrong.

It adds whatever fields you choose to install to the product setup page in Zen Cart, and also adds controls to the other modules IF you have them installed.