**Warning**: This is a mode selector, not a data reference!

**Valid Values**:
- `embedding`: Display attributes of the current page (the page containing this widget)
- `absolute`: Display attributes of a specific page selected explicitly (requires `absoluteSelection`)
- `relative`: Display attributes of a page referenced via an attribute on the current page (requires `relativeSelection`)

**Note**:
- Choosing `absolute` activates the `absoluteSelection` attribute
- Choosing `relative` activates the `relativeSelection` attribute
- Choosing `embedding` requires no additional configuration
- This controls which selection attribute becomes active/required