The Cross Process Correlation Headers Protocol is used to transport custom data by leveraging the capability of [Cross Process Propagation Headers Protocol](Skywalking-Cross-Process-Propagation-Headers-Protocol-v3.md).
This is an optional and additional protocol for language tracer implementation. All tracer implementation could consider to implement this.
Cross Process Correlation Header key is `sw7-correlation`. The value is the `encoded(key):encoded(value)` list with elements splitted by `,` such as `base64(string key):base64(string value),base64(string key2):base64(string value2)`.
Cross Process Correlation Header key is `sw8-correlation`. The value is the `encoded(key):encoded(value)` list with elements splitted by `,` such as `base64(string key):base64(string value),base64(string key2):base64(string value2)`.
## Recommendations of language APIs
Recommended implementation in different language API.
