The following 5 were selected by Just Enough Structured Analysis.
- The more specialized a system is, the less able it is to adapt to different circumstances
- The larger a system gets, the more of its resources must be devoted to its everyday maintenance
- Systems are always part of larger systems and always have smaller ones inside them
- Systems grow - man-made systems especially tend to increase in size over time
- The interactions between systems components are often subtle and complex