Rule Library
Rule Library in the main sidebar holds the Rules you have saved, so you can bring the same standards into every Project. Adding one to a Project gives it an independent copy, so editing either side never changes the other.
Save Rules to the Library
From a Rule's page, Save to Library. On the Rule Library page, Copy Rules from a Project saves Rules you already wrote for a Project into your Library.
Add a Rule to a Project
Open Maintain, then Create rule, and choose Add from your Rule Library.
Write a Rule in the Library
Write a Rule opens the editor: describe the Rule in Markdown, or upload a file. Saved Rules follow you to every Project.
Next step
See Rules for what a Rule contains and how it is scanned.