self add: (Kernel Array new: 4)
This looks like how GNU Smalltalk handles namespaces. Following up the references in the gst info files, I found some discussion on the Squeak wiki which includes some work done by Augustin Mrazik in 1992:
GNU Smalltalk supports both "Kernel Array" and "Kernel.Array". The former is late (run-time) bound, the latter is compile-time bound using the same old "store an association in the method" technique as Squeak.
Paolo