I was looking at the text of the CC BY-SA 4.0 license, which is the license used by posts on the SE network. Specifically, I noted the phrase that...
You must give appropriate credit, provide a link to the license, and indicate if changes were made.
Some of the articles in the help center are editable by moderators, such as /help/on-topic on every site. However, when viewing the page, there is no indication that it has been edited, nor by whom, nor a link to the license. There is a revision history, but it's only visible to moderators and also doesn't clarify what license is being used.
For most posts, the current license is available at /posts/<ID>/timeline, but that page leads to a 404 for help center articles.
At the bottom of the page there's the standard "user contributions licensed under CC BY-SA", but nothing indicating that the help center falls under "user contributions", since most help center articles aren't user-contributed and presumarly do not fall under the CC BY-SA license.
Could the licensing of the help center articles please be clarified?
ContentLicense
column which holds the license type for the post. You can observe this via SEDE, which would answer this question– except for the fact that some types of posts are missing from the public dataset, seemingly including traditional wiki pages like that post #2600 on literature. Maybe that's a way staff could check this internally though?