What is the fine-grained topic of the following text: Open Source Software is adopted in the DBE/OPAALS projects as the best support for sustainability of such complex electronic webs, since it minimises interoperability problems, enables code access for cheaper in-house modification or development of systems, and reduces both capital and operating expenditure. Only return the topic.
Adoption of Open Source Software in DBE/OPAALS projects for sustainability and cost-effectiveness