VMS Help LINK, Parameters  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 file-spec

    Specifies one or more input files (wildcard characters are not
    allowed). Input files can be object modules, shareable images,
    libraries to be searched for external references or from which
    specific modules are to be included, or options files to be read
    by the linker. Separate multiple input file specifications with
    commas (,)  or plus signs (+). In either case, the linker creates
    a single image file.

    If you omit the file type in an input file specification, the
    linker supplies default file types, based on the nature of the
    input file. For object modules, the default file type is .OBJ.