Companion types value 2 means HTML Resource
HTML resource: an HTML fragment supplied in the VAST document and inserted by the player.
When to send it
Send 2 when the companion slot can render an HTML fragment carried inside the VAST document. Web players and in-app SDKs with a web view usually support it. The sample video request in the OpenRTB 2.6 document accepts 1 and 2.
Buyers use HTML companions for richer layouts and their own tracking. It is confused with 3, where the HTML is loaded from a separate URL into an iframe instead of being supplied inline, and with 1 when the creative is only an image.
Example
{
"imp": [
{
"audio": {
"companiontype": [
2
]
}
}
]
}Fields that carry it
Other values in companion types
The companion types list page explains the whole list and its common mistakes.