> For the complete documentation index, see [llms.txt](https://help.dtxplatform.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.dtxplatform.com/publishers-help-center/can-i-set-a-passback-tag-on-my-placement.md).

# Can I set a passback tag on my placement?

Sometimes, we might not be able to ‘fill’ or provide ads in specific regions, browsers or operating systems,\
\
to be able to still provide you with an excellent eCPM and enable you to earn with whoever is able to fill your traffic our team can provide you with a passback tag.\
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A passback tag is an ad tag you provide to us that gets used in the event DTXplatform ads aren’t available at your specified configuration or the bids of the ads we are able to match are below what you’d like to be paid for per impression ('floor bid'). A passback (or alternate/ default) tag can be an ad tag that you received from any other online ad provider that you work with. For instance, if you already have a relationship with Adsterra or PropellerAds, you can give us that ad tag. If DTXplatform can’t find an ad at your specified configuration, we will serve your ad using one of the other tags.\
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DTXplatform enables you to add tags with “passback” functionality for your placement.\
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To request a passback tag added to your placement, please contact <support@dtxplatform.com>\
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The MACROS available for passback tags are below:\
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{pub\_zone} - Publisher zone id\
{subid} - Publisher subid\
{pub\_url} - Referrer URL, (urlencoded)\
{pub\_domain} - Referrer domain, (urlencoded)\
{pub\_redirect} - click redirect URL, (urlencoded, passed from pub tag parameters)\
{pub\_\*} - Custom publisher macros passed from tag parameters, (urlencoded)\
{cachebuster} - Random number


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