I apologize if this has been answered elsewhere, but I couldn't find any mention of this issue either in the errata/faq nor by doing a simple search in the forums.
If I've understood thing correctly specializations gives an edge (represented by a fortune die) when using the skill to do something the specialization refers to. You don't really need to have a specialization to do a specific task, you just become a little bit better.
The Tradecraft skill is listed as having specializations such as Smithing, Engineering, Brewing, Performance. Reading the rules as written then indicates that when you acquire/train the Tradecraft skill (it is an advanced skill) you may do skill tests in all those areas. When you get a specialization you will become slightly better (+1 fortune die) at your specific task, but you're still able to do all the others. This makes little sense to me, even though I agree that grouping up skills is a good thing to limit the clutter, it does get a bit weird when I can become an accomplished blacksmith, brewer and performer just by acquiring one skill.
Just wondering if I've understood things wrongly? In case I'm right it's a simple thing to house rule of course, just treat the listed specializations as separate advanced skills and invent new specializations for each of them.