diff --git a/ENI2/EditControls/EditIMSBCDialog.xaml b/ENI2/EditControls/EditIMSBCDialog.xaml
index e40e216c..0964c8f9 100644
--- a/ENI2/EditControls/EditIMSBCDialog.xaml
+++ b/ENI2/EditControls/EditIMSBCDialog.xaml
@@ -46,7 +46,7 @@
         <TextBox Grid.Row="1" Grid.Column="1" Grid.ColumnSpan="3" Name="textBoxBulkCargoShippingName" MaxLength="255" Margin="2" />
         <CheckBox Grid.Row="2" Grid.Column="1" VerticalAlignment="Center" Margin="2" Name="checkBoxMaterialHazardous" />
         <TextBox Grid.Row="2" Grid.Column="4" Name="textBoxUNNumber" MaxLength="4" Margin="2" VerticalContentAlignment="Center" />
-        <TextBox Grid.Row="3" Grid.Column="1" Name="textBoxIMOClass" MaxLength="4" Margin="2" VerticalContentAlignment="Center" />
+        <TextBox Grid.Row="3" Grid.Column="1" Name="textBoxIMOClass" MaxLength="3" Margin="2" VerticalContentAlignment="Center" />
         <xctk:DoubleUpDown Name="doubleUpDownQuantity" Grid.Row="3" Grid.Column="4" Margin="2" FormatString="N3" ShowButtonSpinner="False" TextAlignment="Left"/>
         <Label Grid.Row="3" Grid.Column="5" Content="kg" />
         <TextBox Grid.Row="4" Grid.Column="1" Name="textBoxStowagePosition" MaxLength="24" Margin="2" VerticalContentAlignment="Center" />
diff --git a/bsmd.database/IGCPosition.cs b/bsmd.database/IGCPosition.cs
index fab5e108..b0b5a354 100644
--- a/bsmd.database/IGCPosition.cs
+++ b/bsmd.database/IGCPosition.cs
@@ -12,6 +12,7 @@ using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Data.SqlClient;
+using System.Text.RegularExpressions;
 using Newtonsoft.Json;
 
 namespace bsmd.database
@@ -27,6 +28,13 @@ namespace bsmd.database
             this.tablename = "[dbo].[IGCPosition]";
         }
 
+        #region static regex
+
+        private static readonly Regex unNumberRegex = new Regex("^[0-9]{4}$");
+        private static readonly Regex imoClassRegex = new Regex(@"^[1-9]{1}(\.[1-9]{1})?$");
+
+        #endregion
+
         #region Properties
 
         [JsonIgnore]
@@ -189,6 +197,20 @@ namespace bsmd.database
 
         #endregion
 
+        #region Validation
+
+        public override void Validate(List<MessageError> errors, List<MessageViolation> violations)
+        {
+
+            if (!this.UNNumber.IsNullOrEmpty() && !unNumberRegex.IsMatch(this.UNNumber))
+                violations.Add(RuleEngine.CreateViolation(ValidationCode.IMPLAUSIBLE, "UNNumber", this.UNNumber, this.Title, this.Identifier, this.HAZ.IsDeparture ? "HAZD" : "HAZA"));
+
+            if (!this.IMOClass.IsNullOrEmpty() && !imoClassRegex.IsMatch(this.IMOClass))
+                violations.Add(RuleEngine.CreateViolation(ValidationCode.IMPLAUSIBLE, "IMOClass", this.IMOClass, this.Title, this.Identifier, this.HAZ.IsDeparture ? "HAZD" : "HAZA"));
+
+        }
+
+        #endregion
 
     }
 }
diff --git a/bsmd.database/IMDGPosition.cs b/bsmd.database/IMDGPosition.cs
index 2243f0b7..fbe1836e 100644
--- a/bsmd.database/IMDGPosition.cs
+++ b/bsmd.database/IMDGPosition.cs
@@ -28,6 +28,13 @@ namespace bsmd.database
             this.tablename = "[dbo].[IMDGPosition]";
         }
 
+        #region static Regex
+
+        private static Regex imoClassRegex = new Regex(@"^[1-9]{1}(\.[1-9]{1}([A-Z]{1})?)?$");
+        private static Regex unNumberRegex = new Regex(@"^[0 - 9]{4}$");
+
+        #endregion
+
         #region Properties
 
         [JsonIgnore]
@@ -507,13 +514,16 @@ namespace bsmd.database
 
             if(!this.IMOClass.IsNullOrEmpty())
             {
-                const string pattern = @"^[1-9]{1}(\.[1-9]{1}([A-Z]{1})?)?$";
-                Regex regex = new Regex(pattern);
-
-                if (!regex.IsMatch(this.IMOClass))
+                if (!imoClassRegex.IsMatch(this.IMOClass))
                     errors.Add(RuleEngine.CreateError(ValidationCode.IMPLAUSIBLE, "IMOClass", null, this.Title, this.Identifier, this.HAZ.IsDeparture ? "HAZD" : "HAZA"));
             }
 
+            if(!this.UNNumber.IsNullOrEmpty())
+            {
+                if(!unNumberRegex.IsMatch(this.UNNumber))
+                    errors.Add(RuleEngine.CreateError(ValidationCode.IMPLAUSIBLE, "UNNumber", null, this.Title, this.Identifier, this.HAZ.IsDeparture ? "HAZD" : "HAZA"));
+            }
+
             if (!this.StowagePosition.IsNullOrEmpty() && (!this.Bay.IsNullOrEmpty() || !this.Row.IsNullOrEmpty() || !this.Tier.IsNullOrEmpty()))
             {
                 errors.Add(RuleEngine.CreateError(ValidationCode.IMPLAUSIBLE, "StowagePosition AND Bay/Row/Tier SET", null, this.Title, this.Identifier, this.HAZ.IsDeparture ? "HAZD" : "HAZA"));
diff --git a/bsmd.database/IMSBCPosition.cs b/bsmd.database/IMSBCPosition.cs
index 9c0ed9d0..5b5098eb 100644
--- a/bsmd.database/IMSBCPosition.cs
+++ b/bsmd.database/IMSBCPosition.cs
@@ -12,6 +12,7 @@ using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Data.SqlClient;
+using System.Text.RegularExpressions;
 using Newtonsoft.Json;
 
 namespace bsmd.database
@@ -22,6 +23,8 @@ namespace bsmd.database
     public class IMSBCPosition : DatabaseEntity, ISublistElement
     {
 
+        #region static defs
+
         public static string[] hazardClass =
         {
             "A",
@@ -29,6 +32,11 @@ namespace bsmd.database
             "A and B"
         };
 
+        private static readonly Regex unNumberRegex = new Regex("^[0-9]{4}$");
+        private static readonly Regex imoClassRegex = new Regex(@"^[1-9]{1}(\.[1-9]{1})?$");
+
+        #endregion
+
         public IMSBCPosition()
         {
             this.tablename = "[dbo].[IMSBCPosition]";
@@ -230,14 +238,13 @@ namespace bsmd.database
         {
             if(!MHB ?? false)
             {
-                if(this.UNNumber.IsNullOrEmpty() || this.IMOClass.IsNullOrEmpty()) 
-                    violations.Add(RuleEngine.CreateViolation(ValidationCode.V803, null, null, this.Title, this.Identifier, this.HAZ.IsDeparture ? "HAZD" : "HAZA"));
-            }
-            if(MHB ?? false)
-            {
-                if(!this.UNNumber.IsNullOrEmpty() || !this.IMOClass.IsNullOrEmpty())
-                    violations.Add(RuleEngine.CreateViolation(ValidationCode.IMPLAUSIBLE, "UNNumber/IMOClass not empty", null, this.Title, this.Identifier, this.HAZ.IsDeparture ? "HAZD" : "HAZA"));
+                if(this.UNNumber.IsNullOrEmpty() || !unNumberRegex.IsMatch(this.UNNumber)) 
+                    violations.Add(RuleEngine.CreateViolation(ValidationCode.V803, "UNNumber", this.UNNumber, this.Title, this.Identifier, this.HAZ.IsDeparture ? "HAZD" : "HAZA"));
+
+                if (this.IMOClass.IsNullOrEmpty() || !imoClassRegex.IsMatch(this.IMOClass))
+                    violations.Add(RuleEngine.CreateViolation(ValidationCode.V803, "IMOClass", this.IMOClass, this.Title, this.Identifier, this.HAZ.IsDeparture ? "HAZD" : "HAZA"));
             }
+            
 
             if (!this.IMOHazardClass.HasValue)
             {