on adding folder items to thisFolder after receiving itemList 
  set addOn to "_A" 
  repeat with aFile in itemList 
    set fullPath to (aFile as string) 
    if fullPath ends with ":" then 
    else 
      set AppleScript's text item delimiters to {":"} 
      set filePath to text items 1 thru -2 of fullPath 
      set oldName to text item -1 of fullPath 
      if oldName contains "." then 
        set AppleScript's text item delimiters to {"."} 
        set baseName to text items 1 thru -2 of oldName as string 
        set suffix to text item -1 of oldName 
      else 
        set baseName to oldName 
        set suffix to "" 
      end if 
      if character -2 of baseName is not "_" then 
        if suffix is not "" then 
          set newName to baseName & addOn & "." & suffix 
        else 
          set newName to baseName & addOn 
        end if 
        set newPath to (filePath & newName) as string 
        try 
          tell application "Finder" to set name of file fullPath to newName 
        end try 
      end if 
    end if 
  end repeat 
  set AppleScript's text item delimiters to {""} 
end adding folder items to 

on adding folder items to thisFolder after receiving itemList 
  set addOn to "_A" 
  repeat with aFile in itemList 
    set fullPath to (aFile as string) 
    if fullPath ends with ":" then 
    else 
      tell application "Finder" 
        set labInd to label index of file fullPath 
      end tell 
      if labInd is 0 then 
        set AppleScript's text item delimiters to {":"} 
        set filePath to text items 1 thru -2 of fullPath 
        set oldName to text item -1 of fullPath 
        if oldName contains "." then 
          set AppleScript's text item delimiters to {"."} 
          set baseName to text items 1 thru -2 of oldName as string 
          set suffix to text item -1 of oldName 
          set newName to baseName & addOn & "." & suffix 
        else 
          set baseName to oldName 
          set newName to baseName & addOn 
        end if 
        set newPath to (filePath & newName) as string 
        try 
          tell application "Finder" to set properties of file fullPath to {name:newName, label index:6} 
        end try 
      end if 
    end if 
  end repeat 
  set AppleScript's text item delimiters to {""} 
end adding folder items to