Course reports
From MoodleDocs
A course report plugin is just another folder inside course/report/. It follows standard plugin practice and may have lang, db etc. sub-folders if these are required. A version.php file must be included.
A mod.php file must be included. This is responsible for creating the HTML fragment that will appear on the course report page as one of the report options. This can be anything. Typically, it will simply generate a link to another page in the report folder (usually index.php) that produces the report. It may, like the logs report generate a form to be completed.
