The general terms and conditions of BITKOM (Bundesverband Informationswirtschaft, Telekommunikation und neue Medien e. V.) issued to t&p on 17.12.2019 (Version 2.1) apply:

Contractual terms for transferring of software (purchase) (english) 43.59 KB 2 downloads
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Contractual terms leasing hardware and standard software (english) 51.31 KB 4 downloads
...(These documents are courtesy translations. The German version of these terms shall be the legally binding version)