Yes, it's stored as [ISBN=??????????] - meaning always some 10-digit number as parameter in the brackets.
I mean, sure, it's not super ugly, but also pointless and makes the main information of that posting missing, which was the product preview.
Thanks for the offer, that would be awseome! I shall come back. Once I have looked at the Books plugin if that's useful for me and if maybe it's possible to replace the old code with something that make it useful for the plugin even.