@maskit brought this up for PR #8015 which addresses issue #4684. The format codes start start with c, but most/all of them really are logging information about the proxy request url.

For the PR @maskit suggests the following which I agree with.

Log field names for content length is very clear. We should have followed this manner.

cqcl | Client Request | Client request content length, in bytes.
pqcl | Proxy Request | Content body length of the Traffic Server proxy request to the origin server.
pscl | Proxy Response | Content body length of the Traffic Server proxy response.
sscl | Origin Response | Content body length of the origin server response to Traffic Server.

We merged the PR since it improved the documentation to reflect reality. Filing this issue to address fixing the underlying implementation to improve a future reality.