If the card you mentioned had a 6 digit alphanumeric number on it then I would say it was the original key fob coding card. The number should match the number printed on a white label inside the key fob on a chip. The EKA code can also be alphanumeric as it is a hexadecimal code, sounds cool just means you have to turn the key more times to enter the code.
Have a look here ( alarm issues) if you cannot get the EKA code. it will explain ways you can get it, as long as the PO has not had it changed.