ISBN  DEFINED
		Our member Selanna-blue is studying library science.  She very kindly composed this explanation of ISBN's.  Thank you Selanna-blue,  I would never have been able to do this without your help.
	"If I may, you state that the ISBN number will vary according to the country of origin. This is partially true as only part of the actual number (before the first hyphen) is dedicated to a country, area or language area participating in the ISBN system. Some members form language areas (e.g. group number 3 = German language group) or regional units (e.g. South Pacific = group number 982). A group identifier may consist of up to 5 digits. All group identifiers are allocated by the International ISBN Agency in Berlin. Further, the second part of the ISBN identifies a particular publisher within a group. The publisher identifier usually indicates the exact identification of the publishing house and its address. If publishers exhaust their initial contingent of title numbers, they may be allocated an additional publisher identifier. The publisher identifier may comprise up to seven digits. Publisher identifiers are assigned by the ISBN group agency responsible for the management of the ISBN system within the country, area or language area where the publisher is officially based. So, what I'm getting at is that this does not mean that an ISBN assigned to a book will vary according to which country this book is sold in, but according to which company actually published said book. Also, several editions of any one title may exist (different format, publisher, etc.), and each will have it's own ISBN. So books found through Amazon.com will likely be from American publishers, while books found on Amazon.co.uk will probably be from UK or European publishers. The best ISBN information can be found through International ISBN Agency http://www.isbn-international.org/index.html  Much of the info just provided comes from there. Also: The National Library of Canada defines an ISBN as: "The International Standard Book Number (ISBN) is a system of numerical identification for books, pamphlets, educational kits, microforms, CD-ROM and braille publications. By assigning a unique ten-digit number to each published title, the system provides that title with its own, unduplicated, internationally recognized "identity". Publishers, booksellers, libraries and other participants in the book industry use ISBN to identify publications in order to expedite their handling and retrieval. ISBN ensures that ordering, inventory control and accounting are executed more efficiently." (http://www.nlc-bnc.ca/6/11/index-e.html) And a very clear but concise explanation can be found courtesy of: isbn.nu http://www.isbn.nu/whatsanisbn.html "An ISBN is an International Standard Book Number. Every book sold anywhere in the world should have a unique ISBN, meaning that you can find any book in the world simply with that one number, which never duplicates. ISBNs are assigned by the Canadian ISBN Agency in Canada http://www.nlc-bnc.ca/isbn/index-e.html, R.R. Bowker in the United States http://www.bowker.com/standards/home/isbn/us/isbnus.html and by a variety of agencies worldwide. Publishers apply to these agencies to get a range of numbers with a unique prefix which varies in length. Because of mergers and acquisitions, some publishers have several, or even dozens of prefixes. Publishers choose what numbers to assign to which books following their prefixes. ISBN have no relationship with subject matter, nor do the dashes mean anything. Every ISBN should be unique. Occasionally, ISBNs are reused for books that have long been out of print, but this practice is generally discouraged. ISBNs are 10 characters long. The first nine characters are chosen as the unique number; the tenth is a checksum."