If you extend a class, and don't want to be able to select the old class in the cms, set this to the old class name. Eg, if you extended Product to make ImprovedProduct, then you would set $hide_ancestor to Product.
Anything that implements HiddenClass won't be shown in user-interface elements. For example, DataObjects that implement HiddenClass won't be showing in the "new page" dropdown.
Identifies if the has a header row.
Determine wether any loaded files should be parsed with a header-row (otherwise we rely on self::$columnMap.
Delegate to different control flow, depending on whether the URL parameter is a number (record id) or string (action).
Delegate to the RecordController if a valid numeric ID appears in the URL segment.