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. For instance, the Windows (WIN32.HLP) and
OS2MAPI are import units.
Of course, 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.
TMT Pascal Language Description
