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

 sine

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

    The sine of the angle whose value (in radians) is to be returned.
    The sine argument is the address of a floating-point number that
    is this sine. The absolute value of sine must be less than or
    equal to 1. For MTH$ASIN, sine specifies an F-floating number.
    For MTH$DASIN, sine specifies a D-floating number. For MTH$GASIN,
    sine specifies a G-floating number.