The contracting authority may reproduce this  Documentation  in full or in part for any  Internal  use  by its staff. The contracting authority shall reproduce all references to  Intellectual  property rights  appearing on the originals.  The contracting authority may decide to assign an identifier to a unit of a delivered  Product .  In such case, the contractor commits itself to using an identifier for every unit of a  Hardware  or  Telecommunications Product  delivered to the contracting authority. This identifier is  communicated to the contractor by the contracting authority when the  Consignment note , or,  if applicable, the  Certificate of Conformity  for such unit has been signed. The identifier(s)  shall be given in electronic file(s) in such manner as shall have been agreed by both  Parties. The contractor’s original identifier mentioned in its delivery documents is associated  with the contracting authority’s identifier. After that, only the contracting authority’s identifier is  to be used in all instances when the contractor refers to the unit in question (for example in  all operations relating to the service desk, invoicing of maintenance, technical intervention,  etc.).  Page 16 of 40  IV.2.9.  Identifiers 