That's inferred. Again, I shouldn't have to infer rules, they are written down to have people conform and abide by them.
lol now you are just being dumb
you can post pictures of spiders, dont post brown town rape gore special interest stuff
dont post gore in general
dont post very graphic images of people getting shot
dont post images of people beating dogs to death for fun
dont post images of close ups of people taking stuffs
if you are actually so stupid that you need to be told
what not to post, then as fawkes said, dont post it at all.