The Marvel Rating System assigns each comic book one of the following ratings:
 
ALL AGES - appropriate for all ages.  
A - Appropriate for age 9 and up.  
T+ TEENS AND UP - Appropriate for most readers 12 and up, parents are advised that they might want to read before or with younger children.  
PARENTAL ADVISORY - 15 years and older. Similar to T+ but featuring more mature themes and/or more graphic imagery.  
MAX: EXPLICIT CONTENT - 18 years old. Most Mature Readers books will fall under the MAX comics banner (created specifically for mature content titles), MAX and Mature-themed titles will continue to be designed to appear distinct from mainline Marvel titles, with the “MAX: Explicit Content” label very prominent on the cover. MAX titles will not be sold on the newsstand, and they will not be marketed to younger readers

It adheres to the comics code, but the books are obviously intended for older fans who get the pop culture references that are in them.

Weird i thought these would be published by Dark Horse

Comics stopped doing the “Comics Code Authority” seals a year or so back.
 
Now they just say “suitible for all ages” on ’em, or something.

IDW doesn’t do anything like the CCA. I think you can tell from the cover what kind of comic you’re getting here.

They only have to adhere to the Universal Comics Code.

*than

I think rating systems for books and comics are vastly different then television and animation.