[slowsmile]

@Evil Overlord...Try the following if you want a new OPF uuid:

* Load your epub template file into Sigil
* Go to the OPF file and delete the "urn:uuid" part from the the uuid value.
* Then run the IDErrorCheck plugin from the Sigil Plugin Index.

The IDErrorCheck plugin will automatically fix and regenerate many incorrect ID errors in your epub -- including the uuids in the OPF and NCX files if they are incorrectly formatted. If you follow the above advice then this plugin should automatically give you a newly generated OPF uuid in the correct format.

And if the OPF uuid is incorrect then the OPF uuid will be replaced and the NCX uuid will also be replaced with the same uuid as the OPF(and vice versa) -- even though this is no longer an IDPF requirement(If the OPF uuid is different from the NCX uuid, Epupcheck no longer gives an error). I learned this from the Epubcheck developer blog after I requested that they fix the "colon" error msg problem some while ago.