For the "Types Tab", the outer list filter as shown below selects each discrete value found in the `type` field. The inner list filter selects all the (non-system) tiddlers with that type.
The list in the "Recent Tab" is generated using the <<.mlink timeline>> macro. Here, the outer list filter selects each discrete day found in the `modified` field, while the inner list filter selects all the tiddlers dated the same day in the `modified` field.
