Set up passback on a Code or Template banner
Let a creative tell the Epom tag it has nothing to show — tick Enable passback functionality, save, copy the Banner passback code into the tag's no-ad path — and the permission and AJAX domain it needs.
Passback lets a creative tell the Epom tag “I have nothing to show”, so the tag can fall through to the next line of demand instead of leaving a blank. It is a per-banner switch on HTML Code banners (Site, Non-standard and Mobile site placements) and Template banners (Site and Non-standard), and it produces a snippet you paste into the creative’s no-ad path. The banner types themselves are on HTML code and Template banners.
Example. Northwind Media’s 300×250 ad-network tag sometimes has no ad. With Enable passback functionality ticked on the HTML Code banner and the Banner passback code pasted into the tag’s no-ad path, the slot is handed back and the next line of demand fills it.
Typical scenarios
| You want | Set | Where |
|---|---|---|
| A third-party tag’s slot to fall through when the tag is empty | Tick Enable passback functionality, save, reopen, paste the Banner passback code into the tag’s no-ad path | Needs the AJAX invocation-code permission and a configured AJAX domain |
| The snippet for a page served from your second AJAX domain | Pick that domain in the Domain list above the block before copying | the saved banner |
| A chain of fallbacks on the placement rather than in the creative | Daisy chaining and passback | the placement |
Step by step
Passback
Passback lets a creative tell the Epom tag “I have nothing to show”, so the tag can fall through to the next line of demand.
- Tick Enable passback functionality above Banner type and Save. The checkbox is shown only to a role holding the AJAX invocation-code permission for the banner’s placement type (Standard, Non-standard or Mobile site), and only once your network has an AJAX invocation-code domain to build the snippet from.
- Reopen the banner: a Banner passback code block appears below the checkbox. With several AJAX invocation-code domains, pick the one your page’s tag is served from in the Domain list above the block; the choice is not saved, so the first domain shows each time.
- Paste the snippet into your creative on the path where it decides not to render. It posts a message up the frame chain that the Epom AJAX tag picks up.
Placement-side fallback chains are a different feature — see Daisy chaining and passback.
Caveats and exceptions
The passback code block only exists on a saved banner. Enable → Save → the block appears; there is nothing to copy while creating. If the network has no AJAX invocation-code domain, the checkbox is not offered at all — ask Epom support or your account manager to set up an AJAX invocation code. A banner that already has passback on keeps the checkbox so you can turn it off.
The caveats that apply to the banner types — who can do this, the Ad unit rules, the type switch — are on HTML code and Template banners.
Not working?
| Symptom | Check | Where |
|---|---|---|
| No Enable passback functionality checkbox | Role lacks the AJAX invocation-code permission for this placement type, the network has no AJAX invocation-code domain, or the placement is Video / Application / Mobile-site Template | Admin → Users & access → User roles & permissions; Epom support for the AJAX domain |
| No Banner passback code block after ticking | The banner is not saved yet | Save, then reopen the banner |
| The passback snippet points at the wrong domain | The Domain list resets to the first entry on every open | Pick the page’s tag domain again before copying |
The rest of the list is on HTML code and Template banners.
Reference
Which placements offer the checkbox for each type: What each placement asks for; the field itself is in Options and fields.
