The owner of this auction refers to them as codificated. He may be able to add some info. His name is Ruben Cameroni.
http://cgi.ebay.com/ARGENTINA-CHIP-CODIFICATED-CASINO-MAR-DEL-PLATA-80s_W0QQitemZ6198914536QQcategoryZ63756QQrdZ1QQcmdZViewItem
