diff --git a/src/Nitload.RegularAnalysis/Abstraction/Mix.cs b/src/Nitload.RegularAnalysis/Abstraction/Mix.cs
index df1ab372..7418472e 100644
--- a/src/Nitload.RegularAnalysis/Abstraction/Mix.cs
+++ b/src/Nitload.RegularAnalysis/Abstraction/Mix.cs
@@ -39,6 +39,8 @@ namespace Nitload.RegularAnalysis.Abstraction
     public interface IMixEvaluator<TElement, TValue>
     {
 
+        public Relation<TElement, TValue, IRelationEvaluator<TElement, TValue>>[] DownstreamPorts { get; }
+
         TValue Evaluate(
                Span<Relation<TElement, TValue>> relations
         );
diff --git a/src/Nitload.RegularAnalysis/PropertyRegex/PropertyEvaluator.cs b/src/Nitload.RegularAnalysis/PropertyRegex/PropertyEvaluator.cs
new file mode 100644
index 00000000..87f7c92a
--- /dev/null
+++ b/src/Nitload.RegularAnalysis/PropertyRegex/PropertyEvaluator.cs
@@ -0,0 +1,25 @@
+// -----------------------------------------------------------------------------
+// file="PropertyEvaluator"
+// Project: StgSharp
+// Copyright (c) Nitload.
+// SPDX-License-Identifier: MIT
+// -----------------------------------------------------------------------------
+
+using Nitload.RegularAnalysis.Abstraction;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Nitload.RegularAnalysis.PropertyRegex
+{
+    internal abstract class PropertyEvaluator<T> : IRelationEvaluator<T, PropertyMatchState>
+    {
+
+        public abstract PropertyMatchState Evaluate(
+                                           ReadOnlySpan<T> sequence
+        );
+
+    }
+}
diff --git a/src/Nitload.RegularAnalysis/PropertyRegex/PropertyMatchEngine.cs b/src/Nitload.RegularAnalysis/PropertyRegex/PropertyMatchEngine.cs
new file mode 100644
index 00000000..b95123f7
--- /dev/null
+++ b/src/Nitload.RegularAnalysis/PropertyRegex/PropertyMatchEngine.cs
@@ -0,0 +1,32 @@
+// -----------------------------------------------------------------------------
+// file="PropertyMatchEngine"
+// Project: StgSharp
+// Copyright (c) Nitload.
+// SPDX-License-Identifier: MIT
+// -----------------------------------------------------------------------------
+
+using Nitload.RegularAnalysis.Abstraction;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Nitload.RegularAnalysis.PropertyRegex
+{
+    public class PropertyMatchEngine<T>
+    {
+
+        private readonly List<Mix<T, PropertyMatchState>> _nodes = [];
+        private readonly List<Relation<T, PropertyMatchState, PropertyEvaluator<T>>> _relations = [];
+
+    }
+
+    public class FrozenPropertyMatchEngine<T>
+    {
+
+        private readonly Mix<T, PropertyMatchState>[] _nodes;
+        private readonly Relation<T, PropertyMatchState, PropertyEvaluator<T>>[] _relations;
+
+    }
+}
diff --git a/src/Nitload.RegularAnalysis/AttributeRegex/PropertyMatchEngine.cs b/src/Nitload.RegularAnalysis/PropertyRegex/PropertyMatchState.cs
similarity index 74%
rename from src/Nitload.RegularAnalysis/AttributeRegex/PropertyMatchEngine.cs
rename to src/Nitload.RegularAnalysis/PropertyRegex/PropertyMatchState.cs
index 8ae52ead..e1fb96d4 100644
--- a/src/Nitload.RegularAnalysis/AttributeRegex/PropertyMatchEngine.cs
+++ b/src/Nitload.RegularAnalysis/PropertyRegex/PropertyMatchState.cs
@@ -1,5 +1,5 @@
 // -----------------------------------------------------------------------------
-// file="PropertyMatchEngine"
+// file="PropertyMatchState"
 // Project: StgSharp
 // Copyright (c) Nitload.
 // SPDX-License-Identifier: MIT
@@ -11,7 +11,7 @@ using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 
-namespace Nitload.RegularAnalysis.AttributeRegex
+namespace Nitload.RegularAnalysis.PropertyRegex
 {
-    internal class PropertyMatchEngine { }
+    internal class PropertyMatchState { }
 }