1. Applicability of the rapid development of today's technology can be applied to technologies and products that access gates are in an endless stream, the project selection systems and products should enable users to gain real benefit, and meet immediate use and long-term development It needs. In many implementations via the selection of the most economically feasible through. 2. Advanced system design and product selection has some advanced technology in use should be in, but not the blind pursuit of new technology is not yet mature or not useful new features to fully protect the user's investment 3. Reliability Systems The design should have a high reliability, after a system failure or an accident caused by an interrupt, to ensure accuracy, completeness and consistency of the data, and with rapid recovery. The standardized, open Standardization, openness is the inevitable trend of information technology, where possible, the conditions used in the design of the product is standardized as far as possible, have a good open, and follow the internationally accepted communication protocol. Application software to maximize the use of common software has been commercialized to reduce the workload of secondary development and conducive to the future use and maintenance. 5. Implementation of the feasibility of existing mature product design as an object, but also taking into account trends in the status of the surrounding environment and information and communication technologies, and to consider centralized management of requirements, so that the design of the program feasible.