A design entity, such as an Altera-provided megafunction or user-created megafunction or macrofunction, that is below another design entity in a project hierarchy. The design entity that contains the subdesign is the parent for that subdesign.
Altera provides libraries of megafunctions and the corresponding AHDL Include Files (.inc) in the \quartus\libraries\megafunctions and \quartus\libraries\others\maxplus2 directories. Component Declarations for functions supported by VHDL are provided in the maxplus2 and megacore packages in the \quartus\libraries\vhdl\altera directory, and in the lpm_components package in the \quartus\libraries\vhdl\lpm directory.