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VHDL also supports descriptions based on a component's underlying internal structure. Structural VHDL allows for sub-components to be instantiated and interconnected. It may be noted that a structural description is similar to a netlist. Of course, the description of the sub-components can themselves be structural and/or behavioral in nature.
RASSP E&F Module 11, Structural VHDL, concentrates on VHDL constructs that support structural descriptions.