Acceptable use of availability attribute 'preorder' value in rich snippets schema markup and Google Shopping feed?

[jeffwhitfield]

Hello all,

Could someone please advise on acceptable use of the availability attribute 'preorder' value in rich snippets schema markup for our websites and the Google Shopping feed?

Currently all of our products are either 'in stock' or 'out of stock', also mentioned was 'available for order' but I found that in the 2014 Google Shopping update, this value will be merged with 'in stock' here 'We are simplifying the ‘availability’ attribute by merging ‘in stock’ with ‘available for order’ and removing ‘available for order’.

The products which we would like to mark as 'preorder' have been in stock and then sold out, however we have a due date for when they will come back into stock, so therefore the customer can preorder the product on our website i.e. pay in advance to secure their purchase and then they are provided with a due date for the products.

Is this the correct use of the 'preorder' value, or does the product literally have to never have been released before? The guidance we have is: 'You are taking orders for this product, but it’s not yet been released.' Is this set in stone?

Many thanks in advance and kind regards.