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

 complex-number

    OpenVMS usage:complex_number
    type:         F_floating complex
    access:       read only
    mechanism:    by reference

    Complex number (r,i). The complex-number argument contains the
    address of this complex number. For MTH$CSQRT, complex-number
    specifies an F-floating number.