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

 angle-in-degrees

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

    The input angle (in degrees). The angle-in-degrees argument is
    the address of a floating-point number which is this angle. For
    MTH$TAND, angle-in-degrees specifies an F-floating number. For
    MTH$DTAND, angle-in-degrees specifies a D-floating number. For
    MTH$GTAND, angle-in-degrees specifies a G-floating number.