Update k-anon check

WICG · JensenPaul · Oct 31, 2023 · Dec 12, 2022 · Dec 13, 2022 · Dec 13, 2022
commit 397e54465a5d40053110125383e965686374dfb0
diff --git a/FLEDGE.md b/FLEDGE.md
@@ -159,7 +159,7 @@ The `sizeGroups` field contains a dictionary of named lists of ad sizes. Each ad
 All fields that accept arbitrary metadata objects (`userBiddingSignals` and `metadata` field of ads) must be JSON-serializable.
 All fields that specify URLs for loading scripts or JSON (`biddingLogicUrl`, `biddingWasmHelperUrl`, and `trustedBiddingSignalsUrl`) must point to URLs whose responses include the HTTP response header `X-Allow-FLEDGE: true` to ensure they are allowed to be used for loading FLEDGE resources.
 
-The browser will provide protection against microtargeting, by only rendering an ad if the same rendering URL is being shown to a sufficiently large number of people (e.g. at least 100 people would have seen the ad, if it were allowed to show). While in the [Outcome-Based TURTLEDOVE](https://github.com/WICG/turtledove/blob/master/OUTCOME_BASED.md) proposal this threshold applied only to the rendered creative, FLEDGE has the additional requirement that the tuple of the interest group owner, bidding script URL, and rendered creative must be k-anonymous for an ad to be shown (this is necessary to ensure the current event-level reporting for interest group win reporting is sufficiently private). For interest groups that have component ads, all of the component ads must also separately meet this threshold for the ad to be shown. Since a single interest group can carry multiple possible ads that it might show, the group will have an opportunity to re-bid another one of its ads to act as a "fallback ad" any time its most-preferred choice is below threshold. This means that a small, specialized interest group that is still below the daily-update threshold could still choose to participate in auctions, bidding with a more-generic ad until the group becomes large enough.
+The browser will provide protection against microtargeting, by only rendering an ad if the same rendering URL is being shown to a sufficiently large number of people (e.g. at least 100 people would have seen the ad, if it were allowed to show). While in the [Outcome-Based TURTLEDOVE](https://github.com/WICG/turtledove/blob/master/OUTCOME_BASED.md) proposal this threshold applied only to the rendered creative, FLEDGE has the additional requirement that the tuple of the interest group owner, bidding script URL, and rendered creative (url+size) must be k-anonymous for an ad to be shown (this is necessary to ensure the current event-level reporting for interest group win reporting is sufficiently private). For interest groups that have component ads, all of the component ads must also separately meet this threshold for the ad to be shown. Since a single interest group can carry multiple possible ads that it might show, the group will have an opportunity to re-bid another one of its ads to act as a "fallback ad" any time its most-preferred choice is below threshold. This means that a small, specialized interest group that is still below the daily-update threshold could still choose to participate in auctions, bidding with a more-generic ad until the group becomes large enough.
 
 
 #### 1.3 Permission Delegation