Anisotropic AND bilinear or trilinear?

The Unity texture inspector shows the Aniso level when either Bilinear or Trilinear filtering are selected. This doesn't make sense to me because a lot of the education I can find on texture filtering methods define Anisotropic to be a third type of filtering, completely separate from Bilinear or Trilinear filtering types.

How can you have both Bilinear AND Anisotropic filtering at the same time? Also, how can you have both Trilinear AND Anisotropic filtering at the same time?