Additional Schema Needed for ItemAvailability

Hello,

I am doing some work on a website for a manufacturer.

Some of the items that exist on the site for purchasing are items that get manufactured once an order is placed.   So.... it would be accurate to have a schema for item availability known as "Built to Order".  The item has not been assembled yet, so "in stock", "backorder", "preorder" and "out of stock" are not accurate.

Please consider adding schema for ItemAvailability as "BuiltToOrder".

Dave