There are scenarios that users wishes to customize their out of stock messages.
Replacing out of stock messages for items on product list pages and product display pages.
Navigate to Commerce > Site Builder > Content > Customize text
Click Messages subtab
There are 4 out of stock messages options available to customize:
(Out of Stock) ITEM-ALLOW/DISALLOW
(Out of Stock) SHOP-ALLOW
(Out of Stock) SHOP-DISSALLOW
(Out of Stock) ITEM-DISSALLOW
The message that would appear is dependent on the setting for Out Of Stock Behavior at Commerce
> Website List
Website > Shopping
If the option is set to Allow backorders but Display out of Stock message, the messages that are entered in 1 is displayed in the item drilldown and 2 in the shopping cart list.
If the option is set to Disallow backorders but Display out of Stock message, the messages that are entered in 1 & 4 are displayed in the item drilldown and 3 is displayed in the shopping cart list.
Note: (About option 3)This option is useful when a webstore customer is utilizing NetSuite for the Shopping Cart & Checkout (WSDK) as it may be set up such that item backorders are disallowed but you may still be able to add items to the shopping cart. In this scenario the message specified in option 3 will display. It would not make sense to specify a customized "out of stock" message for an item that can't be purchased and therefore would not appear in the shopping cart.