Principles
nInformation hiding principle: A module should be able to obtain information from another module only through a well-defined interface between them.
nContinuity principle: A small change
in the specifications should effect only a
few modules in the system, and not the
entire structure of the system.
uStructuring a system around data rather than around functionality measurably enhances continuity.
nOpen-closed principle: The ability to modify or extend a module without affecting other modules.
uA module that still can be modified is said to be open.
uA module that is available for use by other modules is said to be closed.