According to ‘A Guided Tour to the Plane-Based Geometric Algebra PGA’, PGA is applicable to R_{d, 0, 1}. But I am confused about how I can apply PGA to scenario where d > 3.

For example, in 2D PGA:

- Lines are vectors
- Points are bivectors

In 3D PGA:

- Planes are vectors
- Lines are bivectors
- Points are trivectors

How this should look like for 4D PGA? Should I treat volumes as vectors? If so, what should be the geometric interpretation of it?