Definitions must have a name that is composed of three parts: a category, sub-category, and name. The part are separated by periods (like "category.subcategory.name"). The category and sub-category are important because the user can create exceptions and disable definitions by category or sub-category. Therefore, it is important that you use category names that makes sense; otherwise, the user may disable or enable your definition inadvertently.
In some cases a definition may be created for a specific site-group or rule. It is recommended that the definition be named such it is clear it is site-group or rule specific. Oftentimes, this done by appending an underscore to the category name (e.g. "_Acme.InformationLeak.ConfidentialDocumentFound").