Personanondata reports on a study of how ISBNs are being applied to ebooks. It's not, um, the picture of order. Here's the executive summary of the executive summary: "There is wide interpretation and varying implementations of the ISBN eBook standard." And a little more, from the first paragraph:
The ISBN agency is virtually irrelevant to participants and most interviewees—including sophisticated players—do not understand or acknowledge important aspects of the ISBN standard. These aspects include the international community of ISBN countries, the ratification by ISO of the standard and important standard definitions contained in the standard. Many interviewees referred to the ISBN policies and procedures as "recommendations" or "best practices" and without correction each of these issues encourages misinterpretation of the ISBN standard policies.
It's so hard to know what things are when those things are made of information and are only things by analogy.