Also keep in mind that once you choose a specialty branch of a profession, such as goblin or gnomish for engineering, it’s permanent for the life of that character. For example, say you learn goblin engineering. Then you decide to unlearn engineering for whatever reason. Then you decide to take up engineering again with that same character. But this time you want to learn the gnomish branch. You can’t. You chose goblin engineering with that character the first time and that’s what you’re stuck with. So be very sure of your decision when/if that time comes.