core + attic (Attic Area): these terms have been either deprecated from the core or extentions, or removed from pending as not accepted into the full vocabulary.

isbn

Canonical URL: http://schema.org/isbn

Thing > Property > identifier > isbn

The ISBN of the book.

Usage: Between 1000 and 10,000 domains
Values expected to be one of these types
Text
Used on these types
Book
Super-properties
identifier

Schema Version 3.4