plcmt=5 With playbackmethod=1 Validates. Those Two Integers Name Different Formats.
A trafficking template copies last quarter's instream tag, changes one field to pause inventory, and ships. The VAST response validates. The buyer's filter reads plcmt=5 and playbackmethod=1 in the same <Extension> block and treats the impression as a generic instream spot with sound on, not a pause placement with its own playback semantics. Nothing throws a player error because both values are integers inside AdCOM's allowed ranges. The failure is semantic: two signals that were supposed to describe one CTV Ad Portfolio format now describe two different ones. plcmt and playbackmethod answer different questions IAB's CTV Ad Portfolio (finalized July 2026) adds five transactable video formats beyond classic instream: Pause, Screensaver, Overlay, Squeezeback, and In-Scene. OpenRTB carries the buy on video.plcmt values 5 through 9. Downstream of the auction, DSPs echo those signals back into VAST as AdCOM extensions so SSAI paths and measurement vendors that never saw the bid request can still read what was sold. On VAST 4.x the pattern is one signal per extension: <Extensions> <Extension type= "plcmt" ext= "adcom" ><plcmt> 5 </plcmt></Extension> <Extension type= "playbackmethod" ext= "adcom" ><playbackmethod> 9 </playbackmethod></Extension> </Extensions> On VAST 2.0 the same five formats can ship inside a single back-port container ( type="ctv_ad_portfolio" ) with plcmt , playbackmethod , MediaFiles , and Duration in one block. The signaling table is the same; only the XML shape differs. plcmt names the format row: 5 is Pause, 6 is Screensaver, 7 is Overlay, 8 is Squeezeback, 9 is In-Scene. playbackmethod is older AdCOM vocabulary. For legacy instream it still means things like autoplay with sound on (1) or click-to-play (2). The portfolio guidance assigns new playbackmethod values to Pause and Screensaver because those rows needed sound-on and sound-off variants that did not exist in the pre-portfolio table: plcmt Format playbackmethod (firm mapping) 5 Pause 8 (sound