Various links and papers are useful for reference about space filling curves and L-systems.
The white page from which I took most of the SFC L-systems configurations.
This book chapter on plant structure presents various L-systems that draw space-filling curves (for example, the quadratic Gosper and the Peano curve). See also the full book index. This essay shows a stable Hilbert curve, and provides an L-system representation for it (unfortunately, not compatible with our implementation). This essay shows many variants of Hilbert curves that go from a specified point to another (without L-systems).
A page about SFC from the FRACTINT documentation shows many L-systems (and, like many pages about fractals, seems to come from the nineties). A huge page about fractals and SFC with many drawings, especially full of node- and edge-rewriting rules.
This StackOverflow post discusses the idea of having a mapping from an N-dimensional space to 1D by using a Hilbert curve (then an SFC layout can be used to map the data in 2D).