iBooks/epub query

[fred_mouse]

I get a lot of ePub format ebooks, from a range of sources, and I've reached the point where I can't use the 'Categories' option for sorting them in iBooks, because they aren't standardised in any way. For example, there is 'Fantasy', 'fantasy', 'Fantasy--fiction', and a number of other options with the word fantasy included somewhere in the category. So far, I haven't worked out how to hack this data, or any useful way of working with it.

Has anyone found anything useful to do with the categories option? Ways to change the meta-data into something consistent? Anything?