The CAT project file (*.cat.yaml) is the single input every CAT tool opens: which data to connect to, what to test, where the results go, all in one file or pointed to from it. Without it there is nothing to run. Use this skill whenever you create a project, read or restructure a project file, move definitions into other files or a database, or a tool says it cannot open the project; the content of data sources, tests and outputs each have a skill of their own.
