The International Standard Thesis Number (ISTN) system is a global identification system for thesis. Is a numeric thesis identifier which is intended to be unique. It is primarily intended for use by universities, institutes, bibliographic services, libraries and rights management agencies. An ISTN is assigned to each separate edition and variation (except reprinting) of a thesis. For example, an e-thesis, a paperback and a hardcover edition of the same thesis will each have a same ISTN.