chromium-params.md

The draft Attribution Reporting API specification defines a number vendor-specific values.

Chromium's implementation assigns the following values:

Name	Value
Max pending sources per source origin	4096
Max settable event-level epsilon	14
Randomized null attribution report rate excluding source registration time	0.05
Randomized null attribution report rate including source registration time	0.008
Max event-level reports per attribution destination	1024
Max aggregatable attribution reports per attribution destination	1024
Max aggregatable reports per source	20 attribution reports, 5 debug reports
Max destinations covered by unexpired sources	100
Destination rate-limit window	1 minute
Max destinations per rate-limit window	50 per reporting site, 200 total
Max destinations per reporting site per day	100
Max source reporting origins per rate-limit window	100
Max source reporting origins per source reporting site	1
Origin rate-limit window	1 day
Max attribution reporting origins per rate-limit window	10
Max attributions per rate-limit window	100
Randomized aggregatable attribution report delay	10 minutes
Max event-level channel capacity for navigation sources	11.5 bits
Max event-level channel capacity for event sources	6.5 bits
Max unique attribution scope sets per navigation	1
Max trigger-state cardinality	4,294,967,295 (max unsigned 32-bit integer)
Max event-level channel capacity for navigation sources with attribution scopes	11.55 bits
Max event-level channel capacity for event sources with attribution scopes	6.5 bits