Four fields in one value
adfox;moscow;discount;top is the value in Yandex's own example, and it reads left to right. Yandex Metrica, Yandex's web analytics tool, defines the Openstat format as _openstat=openstat_service;openstat_campaign;openstat_ad;openstat_source, with a semicolon between each field:
- adfox: openstat_service, the traffic source
- moscow: openstat_campaign, the campaign ID
- discount: openstat_ad, the ad ID
- top: openstat_source, the site ID
The value holds no field names, only positions, so the order is what tells you which part is the campaign and which is the ad.
The first field has to match a list
Metrica credits the right source only when openstat_service holds a value it recognizes. Yandex publishes the list: adfox for AdFox, admitad for Admitad, criteo for Criteo, taboola for Taboola, tiktok for TikTok, google for Google, and dozens more. For email newsletters, Yandex says to put email or e-mail in openstat_service or openstat_source. When an ad system does not add a tag of its own, Yandex suggests building the link by hand with UTM or Openstat tags.
Only the first page counts
Metrica "gets tag information from the first pageview in a user's session. If there isn't a tag in the first pageview, it isn't detected for the entire session." So a hop that drops the query string before the first tracked page can cost the whole visit its source. Yandex also notes tag content is recognized correctly only on sites that use UTF-8 encoding.
Taking it off
The destination is identical with or without _openstat. Its four fields describe a source, a campaign, an ad and a site, so there is no personal identifier in the format. Deleting it only costs the site owner the source, campaign and ad breakdown in Metrica. Yandex's own ad clicks carry a different tag, yclid, and clicks from its marketplace carry ymclid.