The data validation solution works well as long as I am manually entering the
data. Any ideas how I can maintain the validation rules when copying and
pasting from another external sheet?
You can do that with an event-triggered macro.
Right-click on the worksheet tab, and select View Code
Paste the code below into the window that opens.
Read the comments in the code and make the appropriate changes.
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Option Explicit
Private Sub Worksheet_Change(ByVal Target As Range)
Dim re As Object
Dim c As Range
Const sPattern As String = "[^A-Za-z0-9]"
Set c = [a1] 'set this to the cell you wish to validate
'if there is more than one cell, this can
'be set to a range, but you will then need
'a loop below to check each cell in the range
Set re = CreateObject("vbscript.regexp")
re.Global = True
re.Pattern = sPattern
If re.test(c.Text) = True Then
MsgBox ("Illegal Characters")
c.ClearContents
End If
End Sub
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--ron