VMS Help RTL Routines, MTH$, MTH$xTANH, 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 that contains this input
    value. For MTH$TANH, floating-point-input-value specifies an
    F-floating number. For MTH$DTANH, floating-point-input-value
    specifies a D-floating number. For MTH$GTANH, floating-point-
    input-value specifies a G-floating number.