At Cylc 8 we have switched from the .rc to .cylc file extension.
This makes it easier for text editors and other systems (including Cylc itself) to identify Cylc files for the purposes of things like validation and syntax highlighting.
Cylc provides text editor plugins for VSCode, [Neo]Vim, Emacs and others which have all been updated to work with the new .cylc file extension. For details installations see:
When upgrading Cylc 7 workflows to run in Cylc 8 (without compatibility mode), it’s worth renaming any Cylc include files to use the new .cylc file extension. These files will then be correctly associated by text editors and will be scanned by cylc lint.
If you’ve ever encountered files named something like runtime-suite.rc, the -suite bit was probably put there to make it easier for text editors to identify Cylc files using a pattern (e.g. *suite.rc). This pattern is no longer required so the -suite bit can be removed (e.g. runtime.cylc).