**Default Behavior**: When left empty, the widget displays an attribute from the page where it is embedded.

**Valid Values**:
- Empty/null: Use the current (embedding) page
- Page UID: Reference to a specific page whose attribute should be displayed

**Warning**: When embedded inside a `cf.platform.attributesGroup` widget, omit this key entirely (or leave it empty) - the parent widget provides the target entity. Passing a value here causes a validation error.

**Note**: This parameter is hidden from the edit UI when the widget is embedded inside `cf.platform.attributesGroup`.