So, if I'm reading http://www.gamepur.com/news/20145-fallout-4s-xp-system-working-revealed-there-are-275-separate-xp-levels-one.html correctly, Perks have their own XP levels?! That's news to me, I thought there were just ranks. So, Perks gain XP by us using them in-game similar to Skyrim's Skills or...is this is just a confusing way to say they're just "ranked" perks..
"Some interesting new details has been revealed related to the working of Fallout 4 in the latest issue of OPM. The publication confirmed that Fallout 4 will have 275 separate XP levels, one for each individual perk. You'll still level up via XP, and each level increase will still give you a point to spend on a perk, but now those perks have varying XP levels of their own. In simple term this means, in Fallout 4, each individual perk will carry its own XP levels and it will be tied into player's overall XP rank."