!!! Overview [1]
[{$pagename}] is a component of the [GS1] [Global Trade Item Number] and is a [Unique Identifier] assigned by the manufacturer represented by the [GS1] [GS1 Company Prefix]

[{$pagename}] immediately follows manufacturer code. The total length of [GS1 Manufacturer Code] plus [{$pagename}] should be 9 or 10 digits depending on the length of [GS1 Company Prefix] (2-3 digits).

In [ISBN], [ISMN] and [ISSN], [{$pagename}] is a [Unique Identifier] the publication from the same publisher; it should be used and allocated by the registered publisher in order to avoid creating gaps; however it happens that a registered book or serial never gets published and sold.

!! More Information
There might be more information for this subject on one of the following:
[{ReferringPagesPlugin before='*' after='\n' }]
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* [#1] - [International_Article_Number|Wikipedia:International_Article_Number|target='_blank'] - based on information obtained 2017-10-28-