diff --git a/validation/0005/index0.heta b/validation/0005/index0.heta
new file mode 100644
index 0000000..21d857a
--- /dev/null
+++ b/validation/0005/index0.heta
@@ -0,0 +1,27 @@
+/*
+    Write model in heta code that describes:
+    three compartments: comp1, comp2, comp3
+    four species: c1 (in comp1), c2 (in comp2), c3 (in comp3), a2 (in comp2, amount)
+    three reactions: r1 (c1 -> c2), r2 (c2 -> c3 + a2), r3 (c3 ->)
+*/
+//index.heta
+
+comp1 @Compartment .= 1;
+c1 @Species {compartment: comp1} .= 10;
+
+comp2 @Compartment .= 2;
+c2 @Species {compartment: comp2} .= 0;
+a2 @Species {compartment: comp2, isAmount: true} .= 0;
+
+comp3 @Compartment .= 3;
+c3 @Species {compartment: comp3} .= 0;
+
+// reactions
+r1 @Reaction {actors: c1 = c2} := k1 * c1 * comp1;
+r2 @Reaction {actors: c2 = c3 + a2} := k2 * c2 *comp2;
+r3 @Reaction {actors: c3 = } := k3 * c3 * comp3;
+
+// constants
+k1 @Const = 0.01;
+k2 @Const = 0.02;
+k3 @Const = 0.03;