/usr/share/k3d/lsystem/abop-block-form.ls is in k3d-data 0.8.0.3-3build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 | # --- L-System Parser/Mutator --- Lj Lapre ----------------------------------
3 # recursion depth
90 # angle
10 # thickness as % of length
A
A=B-F+CFC+F-D&F^D-F+&&CFC+F+B>>
B=A&F^CFB^F^D^^-F-D^|F^B|FC^F^A>>
C=|D^|F^B-F+C^F^A&&FA&F^C+F+B^F^D>>
D=|CFB-F+B|FA&F^A&&FB-F+B|FC>>
@
|