Using the example from the user manual:
function MessageBox(hwnd: pointer; text, caption: string; msgtype: integer): integer; stdcall; external 'User32.dll' name 'MessageBoxA';
in a script.
I tried SelfRegisterAsLibrary(engine) and it complied without error.
In another script:
MessageBox(null,'text','caption',0); <-OK
MessageBoxA(null,'text','caption',0); <-Failed compile
I used SelfRegisterAsLibrary(engine, 'CustomDLL') and it complied without error.
In another script:
CustomDLL.MessageBox(null,'text','caption',0); <-Failed compile
CustomDLL.MessageBoxA(null,'text','caption',0); <-Failed compile