Board Thread:Wiki discussions and announcements/@comment-4022742-20140519231344/@comment-4022742-20140520023815

The crux of the matter here is that you could group and  together for the reason of both being a percentage penetration against their respective resistance type.

You could also group, , and  together for the reason of being items that omit armor partially.

You could even group, , , , , , and  togeter for the reason of being items that omit resistances partially.

All of these options would be 100% correct. Just like taking everything from the second example and putting them in a big pile of "Provides AD". Taking all the items from the third option and throwing them in a big pile of "Offensive Items" is also a valid option.

But right now it's just a free for all with pick and take of whatever you want... There's no consensus of how far the segmentation or grouping should go. Nor is there a guideline to follow to what extend we want the different paths of AD and AP to interact with each other. Because yes, Void Staff is the AP equivalent of the AD Last Whisper, but you can't really compare the AD Last Whisper to the AP Sorcerers shoes.