II.11. AMENDMENTS  II.12. ASSIGNMENT  II.13. FORCE MAJEURE  II.14. LIQUIDATED DAMAGES  II.14.1. Liquidated damages for failure of the contractor to perform obligations within the  applicable time limits Any amendment to the FWC or a specific contract shall be subject of a written agreement between the  parties. A specific contract does not constitute an amendment to the FWC.  II.12.1  The contractor may not assign any of the rights and obligations arising from the FWC, including  claims for payments or factoring, without prior written authorisation from the contracting authority.  In such cases, the contractor must provide the contracting authority with the identity of the intended  assignee.  II.12.2  Any right or obligation assigned by the contractor without authorisation is not enforceable against  the contracting authority.  II.13.1 If a party is affected by force majeure, it must immediately notify the other party, stating the nature  of the circumstances, their likely duration and foreseeable effects.  II.13.2 A party is not liable for any delay or failure to perform its obligations under the FWC if that delay or  failure is a result of force majeure. If the contractor is unable to fulfil its contractual obligations due  to force majeure, it has the right to remuneration only for the supplies/services actually delivered  and which obtain a certificate of conformity.  II.13.3 The parties must take all necessary measures to limit any damage due to force majeure.  For any issues not explicitly regulated by a Service Level Agreement, should the contractor fail to perform its  obligations under the FWC within the time limits set by the FWC or the relevant specific contract, or to deliver  a result for which a firm and binding time limit has been agreed, and without prejudice to the contractor's  actual or potential liability incurred in relation to the FWC or to the contracting authority's right to terminate  the FWC or a specific contract, the contracting authority may impose liquidated damages for each day of  delay applying the following formula:  0.3 x ( V/d ) where:  V  is the price of the relevant purchase or deliverable or result;  d  is the duration specified in the FWC or relevant specific contract for delivery of the relevant purchase or  deliverable or result or, failing that, the period between the date specified in Article I.4.2 and the date of  delivery or performance specified in the FWC or relevant specific contract, expressed in days.  Liquidated damages may be imposed together with a reduction in price under the conditions laid down in  Article II.15.  24 