open system
1. A system with characteristics that comply with specified, publicly maintained, readily available standards and that therefore can be connected to other systems that comply with these same standards.
2. A system that implements sufficient open specifications for interfaces, services, and supporting formats to enable properly engineered applications software:- to be ported with minimal changes across a wide range of systems- to interoperate with other applications on local and remote systems- to interact with users in a style that facilitates user portability [POSIX.0].