What Phil and Laura have written certainly summarises -- and illustrates -- the debate over identifiers.
But the text below (from Phil) is a little misleading.
Whether an ISTC
is a real work Identifier or not is a matter of debate. I disagree that ii
is. It is actually an attribute of the ISBN―-hat is how they are assigned.
Different ISBNs of the same master content might have different ISTC’s.
Translations for instance.
The 'rules' of the ISTC say that translations are by definition different works, and MUST have different ISTCs (though those ISTCs will be related to each other -- one is a 'derived work', and this close relationship is recorded in the registration metadata for the ISTCs themselves). This contrasts with library practice, where 'work' is something at a higher level and two translations are actually termed two 'expressions' of the same 'work'. In library terms, the ISTC is an expression identifier. See the attached PDF (a slide from a training session that I deliver fairly regularly) for a summary of how the <indecs> model on which ISTC and ONIX are based compares with the FRBR library model. There is -- as far as I know -- no public identifier that works at the FRBR:work level, though libraries may have internal IDs.
And I'm pretty sure ISTCs can be assigned without an ISBN (and without any product ID at all, in fact) -- they are not (strictly) an attribute of the ISBN, though they may be presented as such in various systems. They can be registered based on a manuscript, prior to there being a product.
On the other hand, there's no doubt that ISTC has so far proved unpopular among publishers, for some of the reasons Laura and Phil list, and its actual usage is minimal.
Graham
Graham Bell
EDItEUR
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