Difference between "Product Qty Units" and "Products Quantity"

When you add/edit a product in admin, you have these fields to enter:

Product Qty Units
Products Quantity

What is the difference?

If you notice these are not placed close to each other on this page -

Products Quantity = your on hand inventory

Products Qty Units is part of three/four settings and refers to something like:
If you sell in cases of 12 only but priced by single unit then the QtyMin would be 12 and the Products Qty Units would be 12. This forces thae sale in a min of 12 units and then in increments of 12. an order for 13 would not process

kobra:

Products Qty Units is part of three/four settings and refers to something like:
If you sell in cases of 12 only but priced by single unit then the QtyMin would be 12 and the Products Qty Units would be 12. This forces thae sale in a min of 12 units and then in increments of 12. an order for 13 would not process

But why must the customer manually adjust the number. For instance in your case it would be very handy if the number is increased by 12 when the customer press "add this to my cart". That does not happen if
"Products Quantity Box Shows:" is set to no.

What does the setting "Product Qty Min/Unit Mix:" control?

What does the setting "Product Qty Min/Unit Mix:" control?
These force the sale in a min of ?? units and then in increments of ??. an order for a value that does not match the min order amd/or the units sold in would not process

kobra:

These force the sale in a min of ?? units and then in increments of ??. an order for a value that does not match the min order amd/or the units sold in would not process

Not correct.
The setting "Product Qty Min/Unit Mix:" set to "yes" allows different option values for the product. In other words if min=2, unit=2 and
"Product Qty Min/Unit Mix:" set to "yes" then you are allowed to buy 2 products with different option values for its attributes.

See the wiki on this - Attributes wiki

While doing a bit of research on this I came across this thread and would like to clarify a bit with my experience. This testing was done on 1.3.8a and could change with any future releases. (2.0 ??? :D)

Assuming boxes of 12 are used and that the Product Qty Units has been set to 12

As David Bo says, on the product detail page Zen-Cart will allow you to add quantities of products to cart that do not follow the rules that one would expect.

Only when proceeding through the checkout process from your shopping cart page does Zen-Cart perform any checks. It will not allow the customer to proceed to checkout if the quantity is not an increment of 12.

I feel this is not an ideal solution. As David Bo mentions if "Products Quantity Box Shows:" is set to no the cart needs to add an incremental value of 12 each time the "Add to Cart" button is pressed.

Also I feel that if the "Products Quantity Box Shows:" is set to show, a drop down menu with only increments of 12 show. The drop down would end at the "Product Qty Maximum:" if it's filled in. And then at the product quantity if that is set. But then if you allow customers to order beyond stock then there needs to be some other value to stop the drop down menu at some point.

Thanks! I didn't realize this was answered until just now. Thanks so much. Reading this thread helps clarify it.

Template Cascade:

I feel this is not an ideal solution. As David Bo mentions if "Products Quantity Box Shows:" is set to no the cart needs to add an incremental value of 12 each time the "Add to Cart" button is pressed.
This is not coded to do this
It is open source and one can custom code to do specific things desired to ones hearts content