clarified possible overlap with os.* attributes, linked to possible v…

…alues

specification/resource/semantic_conventions/browser.md

@@ -18,7 +18,9 @@ All of these attributes can be provided by the user agent itself in the form of
 **[1]:** This value is intended to be taken from the [UA client hints API](https://wicg.github.io/ua-client-hints/#interface) (navigator.userAgentData.brands).
 
 **[2]:** This value is intended to be taken from the [UA client hints API](https://wicg.github.io/ua-client-hints/#interface) (navigator.userAgentData.platform).
-If unavailable, the legacy `navigator.platform` API SHOULD NOT be used instead and this attribute SHOULD be left unset in order for the values to be consistent .
+If unavailable, the legacy `navigator.platform` API SHOULD NOT be used instead and this attribute SHOULD be left unset in order for the values to be consistent.
+
+The list of possible values is defined in the [W3C User-Agent Client Hints specification](https://wicg.github.io/ua-client-hints/#sec-ch-ua-platform). Note that some (but not all) of these values can overlap with values in the [os.type and os.name attributes](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/resource/semantic_conventions/os.md). However, for consistency, the values in the `browser.platform` attribute should capture the exact value that the user agent provides.
 
 **[3]:** The user-agent value SHOULD be provided only from browsers that do not have a mechanism to retrieve brands and platform individually from the User-Agent Client Hints API. To retrieve the value, the legacy `navigator.userAgent` API can be used.
 <!-- endsemconv -->