addresses part of the feedback

semantic_conventions/http-common.yaml

@@ -42,17 +42,21 @@ groups:
         brief: 'HTTP request method.'
         examples: ["GET", "POST", "HEAD"]
         note: |
-          HTTP request method SHOULD be one of the methods defined in [RFC9110](https://www.rfc-editor.org/rfc/rfc9110.html#name-methods)
-          or the PATCH method defined in [RFC5789](https://www.rfc-editor.org/rfc/rfc5789.html).
-
-          General-purpose HTTP instrumentations SHOULD allow overriding the list of known HTTP methods with OTEL_INSTRUMENTATION_HTTP_KNOWN_METHODS environment variable,
-          containing a comma-separated list of case-sensitive known HTTP methods.
+          HTTP request method value SHOULD be known to the instrumentation.
+          By default, this convention defines "known" methods as the ones listed in [RFC9110](https://www.rfc-editor.org/rfc/rfc9110.html#name-methods)
+          and the PATCH method defined in [RFC5789](https://www.rfc-editor.org/rfc/rfc5789.html).
 
           If the HTTP request method is not known to instrumentation, it MUST set the `http.request.method` attribute to `other` and, if it reports spans, MUST
           populate the exact method passed in the request line on `http.request.method_original` span attribute.
 
+          If the HTTP instrumentation could end up converting valid HTTP request methods to `other`, then it MUST provide a way to override
+          the list of known HTTP methods. If this override is done via environment variable, then the environment variable MUST be named
+          OTEL_INSTRUMENTATION_HTTP_KNOWN_METHODS and support a comma-separated list of case-sensitive known HTTP methods
+          (this list MUST be a full override of the default known method, it is not a list of known methods in addition to the defaults).
+
           HTTP method names are case-sensitive and `http.request.method` attribute value MUST match a known HTTP method name exactly.
           Instrumentations for specific web frameworks that consider HTTP methods to be case insensitive, SHOULD populate a canonical equivalent.
+          Tracing instrumentations that do so, MUST also set `http.request.method_original` to the original value.
       - id: response.status_code
         type: int
         requirement_level: