diff --git a/work/projects/cpm-m3-telemetry-privacy-triage.md b/work/projects/cpm-m3-telemetry-privacy-triage.md
index 030ee2d6..4701220f 100644
--- a/work/projects/cpm-m3-telemetry-privacy-triage.md
+++ b/work/projects/cpm-m3-telemetry-privacy-triage.md
@@ -70,7 +70,16 @@ Example: `view@-60,died_crash@-42,error_background_failed_to_load@-41`.
 | `reload_phase` | `unload`, `load`, `lightweight_load`, `full_load`, `fallback_load` |
 | `reload_error` | `already_loaded`, `not_loaded`, `base_url_in_use`, `no_background_content`, `background_failed_to_load`, `unknown`, `other` |
 
-These are allowlisted enums; this pixel does not send raw error domains, codes or messages.
+The four fields above are allowlisted enums. The pixel also sends standard error parameters:
+
+| Parameter | Values |
+|---|---|
+| `d` (`errorDomain`) | Original NSError domain, without category mapping. |
+| `e` (`errorCode`) | Original numeric NSError code. |
+| `ud` (`underlyingErrorDomain`) | Immediate underlying NSError domain, when present. |
+| `ue` (`underlyingErrorCode`) | Immediate underlying numeric code, when present. |
+
+Unknown domains/codes are preserved even when `reload_error=other`. Localized descriptions, file paths and other userInfo contents are not serialized. The underlying error chain is not traversed beyond the immediate error.
 
 ## Testing