|
Every epub requires a unique uuid based identifier whose "id" attribute is specified in the content.opf package tag. This id (in your case "BookId") points to the metadata with the required uuid. Please note, font obfuscation based schemes (both Adobe and IDPF) use this uuid to handle obfuscating and de-obfuscating embedded fonts.
In epub3, this uuid plus the modifier date constitutes a more complete over time unique identifier preventing the constant need to generate a new uuid after each edit or change is made.
It does not show up in the metadata editor to prevent users from deleting it and possibly messing up their epub (especially those with embedded fonts). If you really need to change it, you need to know how to link it to the package tag properly but only after de-obfuscating any embedded fonts.
KevinH
|