Format Object
Fields marked with an asterisk (*) are optional.
Either w/h or wratio/hratio/wmin set should be specified.
| Field | Type | Details | 
|---|---|---|
| h* | integer | Height of the impression in pixels, for example  | 
| w* | integer | Width of the impression in pixels, for example  | 
| hratio* | integer | Relative height when expressing size as a ratio | 
| wratio* | integer | Relative width when expressing size as a ratio | 
| wmin* | integer | The minimum width in device independent pixels (DIPS) at which the ad will be displayed the size is expressed as a ratio. | 
{
  "format":[
    {
      "w":300,
      "h":250
    },
    {
      "w":300,
      "h":900
    }
  ]
}