An Advar template always consists of two files:
The creative's actual content that contains parameters that refer to the properties of an uploaded creative and its files. Besides any custom parameter defined by the creator of the Advar template, the creative content can also contain a number of fixed parameters.
A descriptive file that generates the form that a user will see and need to fill in when uploading a creative. This file contains a JSON object that defines the different elements available in the template. It will determine how to render the form to the user.
As with templates, an Advar template can also contain a request element as a parameter. An Advar template can use all request properties as content. For example, the creative can display the name of the visitor if the call to the ad server contains this parameter (and if the value of the name is available, of course).