use set-cookie format

specification/correlationcontext/api.md

@@ -103,7 +103,34 @@ OPTIONAL parameters:
 
 ### Serialization
 
-Until the [W3C Correlation Context](https://w3c.github.io/correlation-context/) specification is recommended for use, Correlation Context should be serialized using [IETF Dictionary](https://tools.ietf.org/html/draft-ietf-httpbis-header-structure-17#section-3.2) as specified in the current draft of [IETF Structured Field Values for HTTP](https://datatracker.ietf.org/doc/draft-ietf-httpbis-header-structure/) with the header name `otcorrelationcontext`.
+Until the [W3C Correlation Context](https://w3c.github.io/correlation-context/) specification is recommended for use, OpenTelemetry `CorrelationContext` implementations MUST be serialized according to the [editor's draft of W3C Correlation Context as of March 27, 2020](https:/w3c/correlation-context/blob/c974664b9ab4d33af6355f1f7f03a2d52c89a99e/correlation_context/HTTP_HEADER_FORMAT.md) using a vendor-specific header name to avoid collisions with the W3C Correlation Context specification should it change in the future.
+
+#### Header Name
+
+`CorrelationContext` implementations MUST use the header name `otcorrelationcontext`.
+
+#### Header Value
+
+`CorrelationContext` MUST be serialized according to the [editor's draft of W3C Correlation Context as of March 27, 2020](https:/w3c/correlation-context/blob/c974664b9ab4d33af6355f1f7f03a2d52c89a99e/correlation_context/HTTP_HEADER_FORMAT.md).
+
+`CorrelationContext` values MUST be serialized as Percent-Encoded UTF-8 strings according to [RFC 3986 Section 2.1](https://tools.ietf.org/html/rfc3986#section-2.1).
+
+#### Example
+
+Correlation Context:
+
+```json
+{
+ "user": "[email protected]",
+ "name": "Example Name"
+}
+```
+
+Header:
+
+```
+otcorrelcationcontext: user=foo%40example.com,name=Example%20Name
+```
 
 ## Conflict Resolution