diff --git a/extra/L-system/models/abop-4/abop-4.factor b/extra/L-system/models/abop-4/abop-4.factor
new file mode 100644
index 0000000000..6b2688a478
--- /dev/null
+++ b/extra/L-system/models/abop-4/abop-4.factor
@@ -0,0 +1,54 @@
+
+USING: accessors ui L-system ;
+
+IN: L-system.models.abop-4
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+: abop-4 ( <L-system> -- <L-system> )
+
+  L-parser-dialect >>commands
+
+  "c(12)&(20)N" >>axiom
+
+  {
+    {
+      "N"
+      "FII[&(60)rY]>(90)[&(45)'(0.8)rA]>(90)[&(60)rY]>(90)[&(45)'(0.8)rD]!FIK"
+    }
+    { "Y" "[c(4){++l.--l.--l.++|++l.--l.--l.}]" }
+    { "l" "g(.2)l" }
+    { "K" "[!c(2)FF>w>(72)w>(72)w>(72)w>(72)w]" }
+    { "w" "[c(2)^!F][c(5)&(72){-(54)f(3)+(54)f(3)|-(54)f(3)+(54)f(3)}]" }
+    { "f" "_" }
+
+    { "A" "B" }
+    { "B" "C" }
+    { "C" "D" }
+    { "D" "E" }
+    { "E" "G" }
+    { "G" "H" }
+    { "H" "N" }
+
+    { "I" "FoO" }
+    { "O" "FoP" }
+    { "P" "FoQ" }
+    { "Q" "FoR" }
+    { "R" "FoS" }
+    { "S" "FoT" }
+    { "T" "FoU" }
+    { "U" "FoV" }
+    { "V" "FoW" }
+    { "W" "FoX" }
+    { "X" "_" }
+
+    { "o" "$t(-0.03)" }
+    { "r" "~(30)" }
+  }
+    >>rules ;
+
+! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+
+: main ( -- ) [ L-system abop-4 "L-system" open-window ] with-ui ;
+
+MAIN: main