diff --git a/proto/policy.proto b/proto/policy.proto
index 9e686f180994be988543ebd9a26dfd31dffed007..c093eb17a67c2b3ff7bfa690ddd639632ae67511 100644
--- a/proto/policy.proto
+++ b/proto/policy.proto
@@ -55,7 +55,7 @@ message PolicyRuleState {
 // Basic policy rule attributes
 message PolicyRuleBasic {
   PolicyRuleId policyRuleId = 1;
-  optional PolicyRuleState policyRuleState = 2;
+  PolicyRuleState policyRuleState = 2; //policy.proto:58:12: Explicit 'optional' labels are disallowed in the Proto3 syntax. To define 'optional' fields in Proto3, simply remove the 'optional' label, as fields are 'optional' by default.
   uint32 priority = 3;
 
   // Event-Condition-Action (ECA) model
diff --git a/proto/uml/pathcomp.png b/proto/uml/pathcomp.png
new file mode 100644
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diff --git a/proto/uml/policy.png b/proto/uml/policy.png
index adbebe89f657a77d40b3ddf8cec95a93951deaf0..845a1e883223d7588ab20afabf559067cdc27454 100644
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