VMS Help RTL Routines, MTH$, MTH$xLOG10, Argument  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 floating-point-input-value

    OpenVMS usage:floating_point
    type:         F_floating, D_floating, G_floating
    access:       read only
    mechanism:    by reference

    The input value. The floating-point-input-value argument is the
    address of a floating-point number. For MTH$ALOG10, floating-
    point-input-value specifies an F-floating number. For MTH$DLOG10,
    floating-point-input-value specifies a D-floating number. For
    MTH$GLOG10, floating-point-input-value specifies a G-floating
    number.