diff --git a/vba_code_kotsu_master.txt b/vba_code_kotsu_master.txt
index 1750480..74a0c49 100644
--- a/vba_code_kotsu_master.txt
+++ b/vba_code_kotsu_master.txt
@@ -151,75 +151,35 @@ Function CleanCSVField(ByVal field As Variant) As String
 End Function
 
 Sub validateDetailData(ByVal ws As Worksheet, ByVal rowNum As Long)
-    ' Check C column not empty
-    If Trim(ws.Cells(rowNum, 3).Value) = "" Then
-        ws.Cells(rowNum, 19).ClearContents
+    ' Check C column - must be 3-digit alphanumeric, required
+    Dim cValue As String
+    cValue = Trim(ws.Cells(rowNum, 3).Value)
+    
+    If cValue = "" Then
+        ws.Cells(rowNum, 2).Value = "C column is required"
         Exit Sub
     End If
     
-    ' Check G, H required and numeric (for composite key)
-    If Trim(ws.Cells(rowNum, 9).Value) = "" Or Not IsNumeric(ws.Cells(rowNum, 9).Value) Then
-        ws.Cells(rowNum, 19).Value = "G column (I) is required and must be numeric"
+    If Len(cValue) <> 3 Then
+        ws.Cells(rowNum, 2).Value = "C column must be 3 characters"
         Exit Sub
     End If
     
-    If Trim(ws.Cells(rowNum, 10).Value) = "" Or Not IsNumeric(ws.Cells(rowNum, 10).Value) Then
-        ws.Cells(rowNum, 19).Value = "H column (J) is required and must be numeric"
-        Exit Sub
-    End If
-    
-    ' Check I (K column) required
-    If Trim(ws.Cells(rowNum, 11).Value) = "" Then
-        ws.Cells(rowNum, 19).Value = "I column (K) is required"
-        Exit Sub
-    End If
-    
-    ' Check J, K required and numeric
-    If Trim(ws.Cells(rowNum, 12).Value) = "" Or Not IsNumeric(ws.Cells(rowNum, 12).Value) Then
-        ws.Cells(rowNum, 19).Value = "J column (L) is required and must be numeric"
-        Exit Sub
-    End If
-    
-    If Trim(ws.Cells(rowNum, 13).Value) = "" Or Not IsNumeric(ws.Cells(rowNum, 13).Value) Then
-        ws.Cells(rowNum, 19).Value = "K column (M) is required and must be numeric"
-        Exit Sub
-    End If
-    
-    ' Check L-P optional but must be numeric if entered
-    Dim col As Long
-    Dim colName As String
-    Dim colLetter As String
-    colLetter = "NOPQR"
-    
-    For col = 14 To 18
-        If Trim(ws.Cells(rowNum, col).Value) <> "" And Not IsNumeric(ws.Cells(rowNum, col).Value) Then
-            colName = Mid(colLetter, col - 13, 1)
-            ws.Cells(rowNum, 19).Value = colName & " column must be numeric"
-            Exit Sub
-        End If
-    Next col
-    
-    ' Check GH composite key duplicate
-    Dim g As String, h As String
-    Dim r As Long
-    Dim lastRow As Long
-    
-    g = Trim(ws.Cells(rowNum, 9).Value)
-    h = Trim(ws.Cells(rowNum, 10).Value)
-    
-    lastRow = ws.Cells(ws.Rows.Count, 3).End(xlUp).Row
-    
-    For r = 7 To lastRow
-        If r <> rowNum And Trim(ws.Cells(r, 3).Value) = Trim(ws.Cells(rowNum, 3).Value) Then
-            If Trim(ws.Cells(r, 9).Value) = g And Trim(ws.Cells(r, 10).Value) = h Then
-                ws.Cells(rowNum, 19).Value = "GH (I,J) combination already exists"
+    If Not IsNumeric(cValue) And Len(cValue) = 3 Then
+        ' Check if all characters are alphanumeric
+        Dim i As Long
+        Dim ch As String
+        For i = 1 To 3
+            ch = Mid(cValue, i, 1)
+            If Not ((ch >= "0" And ch <= "9") Or (ch >= "A" And ch <= "Z") Or (ch >= "a" And ch <= "z")) Then
+                ws.Cells(rowNum, 2).Value = "C column must be alphanumeric"
                 Exit Sub
             End If
-        End If
-    Next r
+        Next i
+    End If
     
     ' Validation passed
-    ws.Cells(rowNum, 19).ClearContents
+    ws.Cells(rowNum, 2).ClearContents
 End Sub
 
 
@@ -241,7 +201,7 @@ Sub validateDetailDataButton()
     errorCount = 0
     For r = 7 To lastRow
         Call validateDetailData(ws, r)
-        If Trim(ws.Cells(r, 17).Value) <> "" Then
+        If Trim(ws.Cells(r, 2).Value) <> "" Then
             errorCount = errorCount + 1
         End If
     Next r