Avoid misreading OpenRTB category fields: `site.pagecat` describes page context, not campaign targeting.; `bcat` lists blocked categories; it’s not evidence of a buyer’s target.; Always verify taxonomy version and field source in OpenRTB 2.6.
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Reading an OpenRTB field without confusing it with a targeting rule

Use site.pagecat to see what an OpenRTB field describes and why it does not prove a buyer's campaign targeting rule.

Supply Chain Desk · · 3 min read

An OpenRTB field carries the information the sender chose to include with an ad opportunity. It does not, by itself, reveal a buyer's campaign targeting or prove that the buyer used the value. Read the full field path, its definition and its taxonomy, then check the actual request and the receiving system's rule.

Read a category field in context

A category value sent with an ad opportunity is the sender's classification, not an independently verified fact. IAB Tech Lab's Ad Product Taxonomy establishes a standardised nomenclature for describing the product or service being advertised within a creative unit, and is primarily used by publishers and SSPs when blocking categories of advertisements.

Read site.pagecat as a page-category field in the site object: it describes page context, not a campaign setting. This article uses OpenRTB 2.6 as its reference release; check that release and the integration documentation for the field's exact type and taxonomy rather than guessing from its name.

Treat Ad Product Taxonomy categories as shorthand: OpenRTB's adomain attribute is the ultimate thing sellers need to use to evaluate advertisers. A buyer might use a category value to allow, exclude or price an opportunity, or might not use it at all.

Keep page-content categories separate from Ad Product Taxonomy 2.0, which describes the product or service advertised within a creative; Content Taxonomy provides a common language for describing content. Do not assign a taxonomy to site.pagecat by analogy: verify the content taxonomy and version used by the integration.

OpenRTB 2.6 Category Field Reference

  • Field: `site.pagecat`Page category context from publisher/SSP
  • Field: `bcat`Blocked advertiser categories (string array); only one of `acat` or `bcat` should be present
  • IAB1Arts & Entertainment
  • IAB7Health & Fitness

Check the field before drawing a conclusion

  1. Locate the object.site.pagecat is website page context. A similarly named field elsewhere may describe another subject.
  2. Read the type and scope.Check whether the field is an array, number or string and whether it applies to the request, an impression or a deal.
  3. Identify the taxonomy.Category IDs need the applicable taxonomy and version. Do not assign a category to an absent optional field.
  4. Identify the source.Record whether the seller classified the page or transformed a classification supplied by someone else.
  5. Check the receiving rule.Obtain the buyer's relevant configuration or decision evidence for the campaign and period, where available.

In OpenRTB 2.6, bcat is a string array of blocked advertiser categories using the specified category taxonomy; only one of acat or bcat should be present. Unlike site.pagecat, bcat describes blocked categories, not page context.

For example, "bcat": ["IAB1", "IAB7"] lists blocked categories. IAB1 is Arts & Entertainment and IAB7 is Health & Fitness; these are bcat examples, not pagecat values or evidence of a buyer's campaign target.

Mappings between taxonomy versions — for example, between Content Taxonomy 1.0 and Ad Product Taxonomy 2.0 — include rows that do not map cleanly. Implementers should review mappings closely before development, and publishers should decide which categories they consider sensitive enough to trigger a manual creative review. Whether a category may be used for a particular purpose still depends on the actual data flow, permissions and rules.

Distinguish a field value from a targeting rule

A request value is not a rule acting on the opportunity, so check the specification release. If a buyer declines a request carrying a page category, do not attribute the decision to that category without evidence. Check whether the buyer received the field, used the same taxonomy, and had no other restriction or eligibility condition. If the field is absent, record missing context rather than labelling the request untargeted.

Look for a buyer-side rule that explicitly uses category values and evidence that it matched; the request alone proves neither. A useful field record includes the full path, specification release, sender, value source and taxonomy. Record how missing values are treated and which receiving rule uses the field.

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