42 Design, development, installation, maintenance and updating of software; computer programming; development of computer platforms; Software as a Service [SaaS]; Blockchain as a Service [BaaS]; certification of data by means of blockchains; data storage by means of blockchains; user authentication services by means of blockchain technology; computer engineering; development of methods for testing software; technical advice and expertise [engineering work]; quality control and technical support in the field of computer systems (engineers' services); consultation on computer projects (engineering work); technical project studies; expertise and research on commercial and industrial company computer systems; computer system analysis services; research, studies and expert appraisals relating to computer resource estimates; studies and expertise relating to computer system development; technical support in information technology (engineering work); advice regarding installation, improvement, modification, migration and use of computer configurations (engineering work); analyzing, optimizing and reorganizing computer systems, namely, managing, monitoring and finalizing computer software and systems (designing and developing computers and software) (engineers' services); advice with respect to computer services, software, computer networks (consultation with respect to software, design and development of computers); management of IT infrastructures on behalf of industrial and/or commercial companies (facility management) (engineering work); assistance with respect to management, follow-up and finalization of computer systems (engineering work).