diff --git a/src/main/cs/SIUnit.cs b/src/main/cs/SIUnit.cs
new file mode 100644
index 0000000..b1d4343
--- /dev/null
+++ b/src/main/cs/SIUnit.cs
@@ -0,0 +1,72 @@
+/*  Original Licensing Copyright
+ * 
+ *  Contains all International System of Units constants and definitions.
+ *  Copyright (C) 2021  DZ-FSDev
+ *  
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+using System;
+
+namespace COM.DZ_FSDev.Physics
+{
+    /// <summary>
+    /// Contains all International System of Units constants and definitions.
+    /// </summary>
+    public abstract class SIUnit : IUnit
+    {
+        private int _order;
+
+        /// <summary>
+        /// Gets the name of this SIUnit.
+        /// </summary>
+        public string Name { get; }
+
+        /// <summary>
+        /// Gets the symbol of this SIUnit
+        /// </summary>
+        public string Symbol { get; }
+
+        /// <summary>
+        /// Gets the Order of this SIUnit.
+        /// </summary>
+        public int Order { 
+            get { return _order; } 
+            private set 
+            {
+                if (value < 0) throw new ArgumentException("Order cannot be zero.","value");
+                _order = value;
+            }
+        }
+
+        public bool CanAdd(IUnit unit)
+        {
+            throw new System.NotImplementedException();
+        }
+
+        public IUnit DivideBy(IUnit unit)
+        {
+            throw new System.NotImplementedException();
+        }
+
+        public IUnit MultiplyBy(IUnit unit)
+        {
+            throw new System.NotImplementedException();
+        }
+
+        public IUnit Pow(decimal exponent)
+        {
+            throw new System.NotImplementedException();
+        }
+    }
+}