The last API version in which this field will be available is
v202105. Starting with v202108, this field will no longer be
available. To control which platforms your proposal line item will
serve on from v202108 onward, please use request platform targeting
in the targeting expression.
Ads serve in a browser.
In-stream video ads serve in a video.
In-stream video ads serve in a game.
Ads serve in a mobile app.
Out-stream video ads serve in a mobile app. Examples include mobile app interstitials and
mobile app rewarded ads.
Out-stream video ads serve in a browser. Examples include in-feed and in-banner video ads.
The value returned if the actual value is not exposed by the requested API version.