7A3 ; 7C22 [Principles of interpretation: observance of good faith; Gap-filling (recourse to general principles on which Convention is based): UNIDROIT Principles referred to as "principles in the sense of Art. 7(2)"];

8C [Interpretation in light of surrounding circumstances];

9C [Practices established by the parties];

14A [Criteria for offer (basic criteria): intention to be bound in case of acceptance];

18A [Acceptance of offer (time and manner): criteria for acceptance]