From Wikipedia (yes, I know, not exactly the most reliable source)
The origins of the Adult Top 40 chart can be traced back to the late 1980s, when several Top 40 stations decided to focus on playing artists in an effort to attract the more desired 25-34 demographic. In 1994, the Adult Top 40 became an official format after years of growth and support from both stations and artists. Most Adult Top 40 stations feature a playlist that include artists such as Lifehouse, Matchbox Twenty, Train, Nickelback, Goo Goo Dolls, Sheryl Crow, Daughtry, Maroon 5, Pink, John Mayer, The Fray, No Doubt, Shania Twain, Avril Lavigne, Kelly Clarkson, Alanis Morissette, Natasha Bedingfield, Jewel, Katy Perry and 3 Doors Down. Its programming is often compared to the musical playlist of the VH1 Channel (as its programming as seen often as a midway point between Top 40 Mainstream and The Adult Contemporary charts). Many Adult Top 40 stations today are a crossover of Hot AC and Top 40 formats, though it's officially classified as a Hot AC format.
Mix is an example of a crossover Hot AC/top 40 station... it is the alternative to WNCI listeners that get tired of hearing the same top 40 over and over. That playlist from Allfird definitely resembles Hot AC but notice you don't see any 80s and you see tunes not every Hot AC station will play:
Beyonce - Single Ladies is the best example here... but even some aren't playing 30 Seconds To Mars.
Mix didn't change their positioner for no reason... they WANT to sound like the "adult WNCI" - notice in some hours you will hear CHR tracks back to back like "Tonight" into "E.T."
Just my two cents.