Clarify content is content

specification/trace/semantic_conventions/http.md

@@ -79,10 +79,10 @@ Note that the items marked with [1] are different from the mapping defined in th
 | `http.status_text` | [HTTP reason phrase][]. E.g. `"OK"` | No |
 | `http.flavor` | Kind of HTTP protocol used: `"1.0"`, `"1.1"`, `"2"`, `"SPDY"` or `"QUIC"`. | No |
 | `http.user_agent` | Value of the HTTP [User-Agent][] header sent by the client. | No |
-| `http.request_content_length` | The size of the request body in bytes. For requests using transport encoding, this should be the compressed size. | No |
-| `http.request_raw_content_length` | The size of the raw request body after transport decoding. Not set if transport encoding not used. | No |
-| `http.response_content_length` | The size of the response body in bytes. For requests using transport encoding, this should be the compressed size. | No |
-| `http.response_raw_content_length` | The size of the raw response body after transport decoding. Not set if transport encoding not used. | No |
+| `http.request_content_length` | The size of the request content in bytes. This is the number of bytes transferred excluding headers. For requests using transport encoding, this should be the compressed size. | No |
+| `http.request_raw_content_length` | The size of the raw request content after transport decoding. Not set if transport encoding not used. | No |
+| `http.response_content_length` | The size of the response content in bytes. This is the number of bytes transferred excluding headers. For requests using transport encoding, this should be the compressed size. | No |
+| `http.response_raw_content_length` | The size of the raw response content after transport decoding. Not set if transport encoding not used. | No |
 
 
 It is recommended to also use the general [network attributes][], especially `net.peer.ip`. If `net.transport` is not specified, it can be assumed to be `IP.TCP` except if `http.flavor` is `QUIC`, in which case `IP.UDP` is assumed.