Over the input validation of an field you can use a @Fomular to post an failure when the User use one of these characters. Use something like this
@If( @Contains(Field_1;"í");@Failure("no í");@Contains(Field_1;"é");@Failure("no é");@Contains(Field_1;"ó");@Failure("no ó");@Success)
If you like to change the characters of exsitings doc, you can use an LS Agent which change characters of the marked documents in a view.
Dim session As New NotesSession
Dim doccol As NotesDocumentCollection
Dim doc As NotesDocument
Dim eval As variant
Set doccol =session.Currentdatabase.Unprocesseddocuments
If doccol.Count =0 Then
MsgBox "please mark docs" ,0, "please mark docs"
Exit sub
End If
Set doc = doccol.Getfirstdocument()
Do Until doc Is Nothing
eval = Evaluate({@Replacesubstring(Field_1;"í":"ó":"é";"i":"o":"e")}, doc)
Call doc.Replaceitemvalue("Field_1", eval)
Call doc.Save(true,false, true)
Set doc = doccol.Getnextdocument(doc)
Loop
To change the characters in a view column just take
@Replacesubstring(columnvalue;"í":"ó":"é";"i":"o":"e")