Add Some Clarification on Reporting IDs, Origin (#837)

* Add Some Clarification on Reporting IDs, Origin

Wanted to add some clarity, which also will serve as a confirmation for a question we've had internally, on any limitations on buyer/seller reporting IDs. Added a few others in the neighborhood while at it.

I do want to point out that the buyer/seller reporting IDs are listed in the full spec (https://wicg.github.io/turtledove/) as USVStrings for object declaration, but then DOMString when passed into reporting functions as browser signals. I do see other values go into browser signals as USVStrings, so it seems like either can go in...is that difference intentional?

* Update FLEDGE.md

Co-authored-by: Paul Jensen <[email protected]>

---------

Co-authored-by: Paul Jensen <[email protected]>

FLEDGE.md

@@ -237,13 +237,13 @@ The `ads` list contains the various ads that the interest group might show.  Eac
 
  * `adRenderId`: A short [DOMString](https://webidl.spec.whatwg.org/#idl-DOMString) up to 12 characters long serving as an identifier for this ad in this interest group. When this field is specified it will be sent instead of the full ad object for [B&A server auctions](https://github.com/WICG/turtledove/blob/main/FLEDGE_browser_bidding_and_auction_API.md).
 
- * `buyerAndSellerReportingId`: If set, the value is used instead of the interest group name or `buyerReportingId` for reporting in `reportWin` and `reportResult`. Note that this field needs to be jointly k-anonymous with the interest group owner, bidding script URL, and render URL to be provided to these reporting fuctions (in the same way that the interest group name would have needed to be).
+ * `buyerAndSellerReportingId`: A [USVString](https://webidl.spec.whatwg.org/#idl-USVString), no character limit. If set, the value is used instead of the interest group name or `buyerReportingId` for reporting in `reportWin` and `reportResult`. Note that this field needs to be jointly k-anonymous with the interest group owner, bidding script URL, and render URL to be provided to these reporting fuctions (in the same way that the interest group name would have needed to be).
 
- * `buyerReportingId`: If set, the value is used instead of the interest group name for reporting in `reportWin`. Note that this field needs to be jointly k-anonymous with the interest group owner, bidding script URL, and render URL to be provided to these reporting fuctions (in the same way that the interest group name would have needed to be).
+ * `buyerReportingId`: A [USVString](https://webidl.spec.whatwg.org/#idl-USVString), no character limit. If set, the value is used instead of the interest group name for reporting in `reportWin`. Note that this field needs to be jointly k-anonymous with the interest group owner, bidding script URL, and render URL to be provided to these reporting fuctions (in the same way that the interest group name would have needed to be).
 
  * `metadata`: Arbitrary metadata that can be used at bidding time.
 
- * `allowedReportingOrigins`: A list of up to 10 destination origins allowed to receive [registered macro values in reporting](https://github.com/WICG/turtledove/blob/main/Fenced_Frames_Ads_Reporting.md#registeradmacro). All origins must be HTTPS and [attested for Protected Audience API](https://github.com/privacysandbox/attestation#the-privacy-sandbox-enrollment-attestation-model).
+ * `allowedReportingOrigins`: A list of up to 10 destination origins allowed to receive [registered macro values in reporting](https://github.com/WICG/turtledove/blob/main/Fenced_Frames_Ads_Reporting.md#registeradmacro). All origins must be HTTPS and [attested for Protected Audience API](https://github.com/privacysandbox/attestation#the-privacy-sandbox-enrollment-attestation-model). Entries are [USVString](https://webidl.spec.whatwg.org/#idl-USVString), no character limit. Invalid URL, non HTTPS, or list size greater than 10, will result in failure to join the interest group.
 
 The `adComponents` field contains the various ad components (or "products") that can be used to construct ["Ads Composed of Multiple Pieces"](https://github.com/WICG/turtledove/blob/main/FLEDGE.md#34-ads-composed-of-multiple-pieces)). Similar to the `ads` field, each entry is an object that includes a `renderURL` and optional `adRenderId`, and `metadata` fields. Thanks to `ads` and `adComponents` being separate fields, the buyer is able to update the `ads` field via the `updateURL` without losing `adComponents` stored in the interest group.