Expanding ads are considered Rich Media. And must be served by trusted Rich Media vendors such as Sizmek, Pointroll, DoubleClick, etc. There are metrics involved with expanding ads that are not something you create yourself.
Here is the link to DCRM templates filtered for Edge Animate
DCRM templates filtered for Expanding as a feature
Wow That would explain the lack of info on the topic~
Thank you very much!
I will get to work now Kate
I would attempt to verify which Rich Media vendor will serve and traffic the ad before building as they all have their own APIs. I like Doubleclick a lot, but honestly have only used Doubleclick and Pointroll. Sizmek, formerly Eyeblaster is still a player. I was also impressed by AdForm's early foray into HTML5.