Template Classification extension
The extension contains code for manual (user) template classification. Classifying templates lets us understand our content better. The extension provides a modal UI with a list of types a user can choose from to determine template type. Is also shows a type label on template page which is an entry point to the edit modal.
More about types and classification can be found on Template types help
Manual vs. machine classification
In parallel to the manual classification that is done by users, a machine classification is done based on some heuristics. Machine classification is not a part of this extension, although a template's classification can fall back to a machine type.
Supported types
Machine classification can have any type and the list keeps expanding. UI supports only certain types defined within this extension to avoid causing a choice paralysis. List of types supported by the manual classification is defined in \UserTemplateClassificationService::$templateTypes.
Storage
Types are stored in TemplateClassification Service. It returns both manual and machine classification where manual has higher priority.