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

 file-spec[, . . . ]
    Specifies one or more files of XREF data to be imported. You can use
    wildcards with the file-spec parameter.

    The default file type is .XREF, which is the default file type for
    XREF data files created by Compaq compilers.