You can place declarations of imported procedures and functions directly in the program that imports them. They are usually grouped together in an "import unit" that contains declarations for all procedures and functions in a DLL, along with any constants and types required to interface with the DLL.

The WinTypes and WinProcs units are import units.

Import units are not a requirement of the DLL interface, but they do simplify maintenance of projects that use multiple DLLs. Also, when the associated DLL is modified, only the import unit needs updating to reflect the changes.