IV.8.3.  Guarantee of proper operation of  Commissioned software  IV.8.3.1.  Except in the case of hidden defects, for which its liability shall be of unlimited duration,  the contractor shall guarantee the proper operation of  Commissioned software . It shall be  held responsible for the immediate repair, at its own expense, of any breakdowns that occur  during the guarantee period, unless it can prove that such breakdowns have occurred for  reasons other than mistakes made in performance of the service, or other than manufacturing  or design errors in that portion of the work for which it was responsible.  IV.8.3.2.  The contracting authority shall notify by a  Means of communication  the contractor of the type  and scale of any failure as soon as it occurs. If the contractor does not repair the  Commissioned software  without delay, the contracting authority may have it repaired by a  third party, on the responsibility and at the own and sole expense of the contractor.  IV.8.3.3.  The Parties shall jointly define and duly record in minutes the major problems that might  affect the  Commissioned software .  IV.8.3.4.  The duration of the guarantee shall be extended by the period which elapses between  the notification of a major problem to the contractor duly sent by the contracting authority  during the stated guarantee period and the date at which the contracting authority accepts the  corrected work.  IV.8.4.1.  Pursuant to the relevant Article of the General Conditions, the contractor hereby assigns to  the contracting authority, which accepts, all  Intellectual property rights  on the  Commissioned  software , for the entire world, for the entire duration of the  Intellectual property rights  involved,  and in an exclusive and definite manner.  IV.8.4.2.  The contracting authority shall become the owner of the source code, results,  Documentation  and sets of tests that correspond to payments already made, except when the same relate to  pre-existing  Software . Further to Article IV.2.3.4, the use of pre-existing  Software  shall be  subject to the contracting authority’s prior written consent.  IV.8.4.3.  The contracting authority shall have the right to disseminate and distribute a  Commissioned  software  to third Parties, even if it contains pre-existing  Software , subject to observance of any  licence terms in respect of third party  Software .  IV.8.5.1.  The contractor shall prepare the manuals and  Documentation needed for the appropriate and  proper operation of the  Commissioned software and shall make them available to the  contracting authority. It shall comply with the provisions under Article IV.10 in preparing such  manuals and  Documentation .  IV.8.5.2.  The material shall as a rule comprise:  (1) an installation manual;  (2) a “Getting Started” manual;  (3) an administration, operation and maintenance manual; Page 37 of 40  IV.8.5.  User manuals and  Documentation IV.8.4.  Intellectual property rights  and ownership of source code 