withindex.js, we have a single source of truth, giving fine grained control on what we expose to the outside world.

In the next major, we'll start copying the ref onto both the props and the element.ref. React will now use the props.ref as the source of truth for forwardRef and classes and it will still create a shallow copy of props that excludes the ref in these cases. At the same time, we'll add a getter for element.ref in DEV that warns if you access it. The upgrade path is now to just access it off props if you need it from the element.

Redux, which features a single store, often called a single source of truth

Do not include the same information in multiple places. Link to a SSOT instead.

There is a temptation to summarize the information on another page. This will cause the information to live in two places. Instead, link to the SSOT and explain why it is important to consume the information

With a single file in the repository, everyone with read access can see the contents, making it much more inviting to improve and review the build scripts.

Code Owners allows for a version controlled single source of truth file outlining the exact GitLab users or groups that own certain files or paths in a repository.