The library argument specifies the name of the DLL. You can also use the /OUT linker option to specify the DLL's output name.
The BASE=address argument sets the base address that the operating system uses to load the DLL. This argument overrides the default DLL location of 0x10000000. See the description of the /BASE option for details about base addresses.
Remember to use the /DLL linker option when you build a DLL.