! *** PREDECLARED TYPES
     
      %IF %DECLARED ( %BASIC$QUADWORD_DECLARED ) = 0 %THEN
         RECORD BASIC$QUADWORD
            LONG FILL ( 2 )
         END RECORD
         %LET %BASIC$QUADWORD_DECLARED = 1
      %END %IF
     
      %IF %DECLARED ( %BASIC$OCTAWORD_DECLARED ) = 0 %THEN
         RECORD BASIC$OCTAWORD
            LONG FILL ( 4 )
         END RECORD
         %LET %BASIC$OCTAWORD_DECLARED = 1
      %END %IF
     
      %IF %DECLARED ( %BASIC$HFLOAT_AXP_DECLARED ) = 0 %THEN
         RECORD BASIC$HFLOAT_AXP
            LONG FILL ( 4 )
         END RECORD
         %LET %BASIC$HFLOAT_AXP_DECLARED = 1
      %END %IF
     
      %IF %DECLARED ( %BASIC$F_FLOATING_COMPLEX_DECL ) = 0 %THEN
         RECORD BASIC$F_FLOATING_COMPLEX
            SINGLE REAL_PART
            SINGLE IMAGINARY_PART
         END RECORD
         %LET %BASIC$F_FLOATING_COMPLEX_DECL = 1
      %END %IF
     
      %IF %DECLARED ( %BASIC$D_FLOATING_COMPLEX_DECL ) = 0 %THEN
         RECORD BASIC$D_FLOATING_COMPLEX
            DOUBLE REAL_PART
            DOUBLE IMAGINARY_PART
         END RECORD
         %LET %BASIC$D_FLOATING_COMPLEX_DECL = 1
      %END %IF
     
      %IF %DECLARED ( %BASIC$G_FLOATING_COMPLEX_DECL ) = 0 %THEN
         RECORD BASIC$G_FLOATING_COMPLEX
            GFLOAT REAL_PART
            GFLOAT IMAGINARY_PART
         END RECORD
         %LET %BASIC$G_FLOATING_COMPLEX_DECL = 1
      %END %IF
     
      %IF %DECLARED ( %BASIC$H_FLOAT_AXP_CMPLX_DCL ) = 0 %THEN
         RECORD BASIC$H_FLOATING_COMPLEX_AXP
            BASIC$HFLOAT_AXP REAL_PART
            BASIC$HFLOAT_AXP IMAGINARY_PART
         END RECORD
         %LET %BASIC$H_FLOAT_AXP_CMPLX_DCL = 1
      %END %IF
    
    
      DECLARE LONG CONSTANT LIB$K_PROC_VALUE_NULL = 0
      DECLARE LONG CONSTANT LIB$K_INVO_HANDLE_NULL = 0
      DECLARE LONG CONSTANT LIBICB$K_INVO_HANDLE_SIZE = 8
      DECLARE LONG CONSTANT LIBICB$K_INVO_CONTEXT_VERSION = 3
    !  The header quadword contains:
      DECLARE LONG CONSTANT LIBICB$M_FFLAGS_BITS = x'00FFFFFF'
      DECLARE LONG CONSTANT LIBICB$M_FRAME_FLAGS = x'00FFFFFF'
      DECLARE LONG CONSTANT LIBICB$M_EXCEPTION_FRAME = x'00000001'
      DECLARE LONG CONSTANT LIBICB$M_AST_FRAME = x'00000002'
      DECLARE LONG CONSTANT LIBICB$M_BOTTOM_OF_STACK = x'00000004'
      DECLARE LONG CONSTANT LIBICB$M_HANDLER_PRESENT = x'00000008'
      DECLARE LONG CONSTANT LIBICB$M_IN_PROLOGUE = x'00000010'
      DECLARE LONG CONSTANT LIBICB$M_IN_EPILOGUE = x'00000020'
      DECLARE LONG CONSTANT UC_MCONTEXT_IREG_RAX = 16
      DECLARE LONG CONSTANT REG_RAX = 0
      DECLARE LONG CONSTANT UC_MCONTEXT_IREG_RDX = 24
      DECLARE LONG CONSTANT REG_RDX = 1
      DECLARE LONG CONSTANT UC_MCONTEXT_IREG_RCX = 32
      DECLARE LONG CONSTANT REG_RCX = 2
      DECLARE LONG CONSTANT UC_MCONTEXT_IREG_RBX = 40
      DECLARE LONG CONSTANT REG_RBX = 3
      DECLARE LONG CONSTANT UC_MCONTEXT_IREG_RSI = 48
      DECLARE LONG CONSTANT REG_RSI = 4
      DECLARE LONG CONSTANT UC_MCONTEXT_IREG_RDI = 56
      DECLARE LONG CONSTANT REG_RDI = 5
      DECLARE LONG CONSTANT UC_MCONTEXT_IREG_RBP = 64
      DECLARE LONG CONSTANT REG_RBP = 6
      DECLARE LONG CONSTANT UC_MCONTEXT_IREG_RSP = 72
      DECLARE LONG CONSTANT REG_RSP = 7
      DECLARE LONG CONSTANT UC_MCONTEXT_IREG_R8 = 80
      DECLARE LONG CONSTANT REG_R8 = 8
      DECLARE LONG CONSTANT UC_MCONTEXT_IREG_R9 = 88
      DECLARE LONG CONSTANT REG_R9 = 9
      DECLARE LONG CONSTANT UC_MCONTEXT_IREG_R10 = 96
      DECLARE LONG CONSTANT REG_R10 = 10
      DECLARE LONG CONSTANT UC_MCONTEXT_IREG_R11 = 104
      DECLARE LONG CONSTANT REG_R11 = 11
      DECLARE LONG CONSTANT UC_MCONTEXT_IREG_R12 = 112
      DECLARE LONG CONSTANT REG_R12 = 12
      DECLARE LONG CONSTANT UC_MCONTEXT_IREG_R13 = 120
      DECLARE LONG CONSTANT REG_R13 = 13
      DECLARE LONG CONSTANT UC_MCONTEXT_IREG_R14 = 128
      DECLARE LONG CONSTANT REG_R14 = 14
      DECLARE LONG CONSTANT UC_MCONTEXT_IREG_R15 = 136
      DECLARE LONG CONSTANT REG_R15 = 15
      DECLARE LONG CONSTANT UC_MCONTEXT_IREG_RIP = 144
      DECLARE LONG CONSTANT REG_RIP = 16
      DECLARE LONG CONSTANT LIBICB$K_PSEUDO_REGS_SIZE = 256
      DECLARE LONG CONSTANT UC_PSEUDO_REGS = 152
      DECLARE LONG CONSTANT UC_MCONTEXT_RFLAGS = 408
      DECLARE LONG CONSTANT UC_MCONTEXT_FS = 416
      DECLARE LONG CONSTANT UC_MCONTEXT_GS = 418
      DECLARE LONG CONSTANT UC_MCONTEXT_MXCSR = 424
      DECLARE LONG CONSTANT UC_MCONTEXT_FCW = 428
      DECLARE LONG CONSTANT UC_MCONTEXT_FSW = 430
      DECLARE LONG CONSTANT LIBICB$K_FXSAVE_SIZE = 512
      DECLARE LONG CONSTANT UC_MCONTEXT_FXSAVE = 432
      DECLARE LONG CONSTANT LIBICB$K_CONTEXT_BLK_SIZE = 504
      DECLARE LONG CONSTANT LIBICB$K_CURSOR_BLK_SIZE = 1024
      DECLARE LONG CONSTANT LIBICB$K_SDA_COPY_LENGTH = 1608
    ! ******* Start of User Override *************************
      DECLARE LONG CONSTANT LIBICB$M_UO_FLAG_CACHE_UNWIND = x'00000001'
      DECLARE LONG CONSTANT LIBICB$M_UO_FLAG_EMULATION_MODE = x'00000002'
      DECLARE LONG CONSTANT LIBICB$K_UO_LENGTH = 88
    ! 
      DECLARE LONG CONSTANT LIBICB$m_using_client_memread = x'00000001'
      DECLARE LONG CONSTANT LIBICB$m_my_mode = x'00000006'
      DECLARE LONG CONSTANT LIBICB$K_REGION_BLK_SIZE = 1096
      DECLARE LONG CONSTANT LIBICB$K_REGIONLABEL_BLK_SIZE = 32
      DECLARE LONG CONSTANT LIBICB$K_DESCRIPTOR_BLK_SIZE = 1280
    !  Action codes:
      DECLARE LONG CONSTANT LIBICB$K_ACTION_KP_FIND_UNWIND = 1  !  override call to exe$kp_find_unwind_context
    !  prototype:
    !    uint64 sp = action_routine (enum action_code code, uint64 sp, uint64 ident);
      DECLARE LONG CONSTANT LIBICB$K_ACTION_USE_DEFAULT = -1  !  action routine return value to "use default"
    !  Alert codes:  (matches _UNW_ReturnCode enum in unwind.h)
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_KRNL_SAV_STATE = -2  !  _UNW_STEP_KERNEL_SAVE_STATE = -2
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_BOTTOM = -1  !  _UNW_STEP_BOTTOM
      DECLARE LONG CONSTANT LIBICB$K_AC_OK = 0  !  _UNW_OK = 0
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_ERROR = 1  !  _UNW_STEP_ERROR
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_INVALID_IP = 2  !  _UNW_STEP_INVALID_IP
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_INVALID_SP = 3  !  _UNW_STEP_INVALID_SP
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_INVALID_GR = 4  !  _UNW_STEP_INVALID_GR
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_INVALID_PFS = 5  !  _UNW_STEP_INVALID_PFS
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_INVALID_RSC = 6  !  _UNW_STEP_INVALID_RSC
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_INVALID_BSP = 7  !  _UNW_STEP_INVALID_BSP
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_INV_BSPSTORE = 8  !  _UNW_STEP_INVALID_BSPSTORE
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_INVALID_CFM = 9  !  _UNW_STEP_INVALID_CFM
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_INVALID_BR = 10  !  _UNW_STEP_INVALID_BR
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_BAD_BSP_ALIGN = 11  !  _UNW_STEP_BAD_BSP_ALIGNMENT
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_INVALID_RNAT = 12  !  _UNW_STEP_INVALID_RNAT
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_NODSC4_NONLEAF = 13  !  _UNW_STEP_NO_DESCRIPTOR_FOR_NON_LEAF
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_CORRUPT_DESC = 14  !  _UNW_STEP_CORRUPT_DESCRIPTOR
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_RSE_NOT_FLUSHD = 15  !  _UNW_STEP_RSE_NOT_FLUSHED
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_SIGNAL_CONTEXT = 16  !  _UNW_STEP_SIGNAL_CONTEXT
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_BAD_STATE = 17  !  _UNW_STEP_NOT_ALLOWED_IN_STATE
      DECLARE LONG CONSTANT LIBICB$K_AC_INIT_RANGE_ERROR = 18  !  _UNW_INITIALIZATION_RANGE_ERROR
      DECLARE LONG CONSTANT LIBICB$K_AC_QUERY_RANGE_ERROR = 19  !  _UNW_QUERY_RANGE_ERROR
      DECLARE LONG CONSTANT LIBICB$K_AC_QUERY_INVALID_ERROR = 20  !  _UNW_QUERY_INVALID_ERROR
      DECLARE LONG CONSTANT LIBICB$K_AC_SET_BAD_STATE = 21  !  _UNW_SET_NOT_ALLOWED_IN_STATE
      DECLARE LONG CONSTANT LIBICB$K_AC_CURR_CTXT_FAILED = 22  !  _UNW_CURRENT_CONTEXT_FAILED
      DECLARE LONG CONSTANT LIBICB$K_AC_CURR_CTXT_BAD_STATE = 23  !  _UNW_CURRENT_CONTEXT_NOT_ALLOWED_IN_STATE
      DECLARE LONG CONSTANT LIBICB$K_AC_MEMORY_ALLOC_ERROR = 24  !  _UNW_MEMORY_ALLOCATION_ERROR
      DECLARE LONG CONSTANT LIBICB$K_AC_CLEAR_BAD_STATE = 25  !  _UNW_CLEAR_NOT_ALLOWED_IN_STATE
      DECLARE LONG CONSTANT LIBICB$K_AC_QUERY_BAD_STATE = 26  !  _UNW_QUERY_NOT_ALLOWED_IN_STATE
      DECLARE LONG CONSTANT LIBICB$K_AC_INTERNAL_ERROR = 27  !  _UNW_INTERNAL_ERROR
      DECLARE LONG CONSTANT LIBICB$K_AC_STEP_I_ABI_MISMATCH = 28  !  _UNW_STEP_INTERRUPTION_ABI_MISMATCH
      DECLARE LONG CONSTANT LIBICB$K_AC_UNALIGNED_ICB = 29  !  _UNW_UNALIGNED_ICB
      DECLARE LONG CONSTANT LIBICB$K_AC_READ_MEM_FAILURE = 30  !  _UNW_READ_MEMORY_FAILURE
      DECLARE LONG CONSTANT LIBICB$K_AC_WRITE_MEM_FAILURE = 31  !  _UNW_WRITE_MEMORY_FAILURE
      DECLARE LONG CONSTANT LIBICB$K_AC_WRITE_REG_FAILURE = 32  !  _UNW_WRITE_REGISTER_FAILURE
      DECLARE LONG CONSTANT LIBICB$K_AC_UO_INCON_CALLBACK = 33  !  _UNW_USER_OVERRIDE_INCONSISTENT_CALLBACK_PARAM
      DECLARE LONG CONSTANT LIBICB$K_AC_PUT_REG_INVALID = 34  !  _UNW_PUT_REGISTER_INVALID
      DECLARE LONG CONSTANT LIBICB$K_INVO_CONTEXT_BLK_SIZE = 1744
      DECLARE LONG CONSTANT LIBICB$S_INVO_CONTEXT_BLK = 1744
      record INVO_CONTEXT_BLK
    ! 
    ! 	 The length of the structure in bytes (a longword field),
    ! 	 The frame flags (a 3 byte field of bits), and
    ! 	 The version number (a 1 byte field)
         group LIBICB$R_HDR
            variant
               case
                  BASIC$QUADWORD LIBICB$IH_HEADER  !  Header (length, flags, version)
               case
                  group LIBICB$R_HDR_DESC
                     LONG LIBICB$L_CONTEXT_LENGTH
                     group LIBICB$R_FRAMEFLAGS
                        variant
                        case
                            !  deprecated, will go away ...
                           BYTE FFLAGS_BITS_bits ( 6 )   ! COMMENT ADDED BY SDL - FFLAGS_BITS_bits contains bits FFLAGS_BITS through
  &
 ! FRAME_FLAGS
                        case
                           group LIBICB$R_FFLAGS_DESC
                              BYTE EXCEPTION_FRAME_bits   ! COMMENT ADDED BY SDL - EXCEPTION_FRAME_bits contains bits  &
 ! EXCEPTION_FRAME through FILL_0_
                           end group LIBICB$R_FFLAGS_DESC
                        end variant
                     end group LIBICB$R_FRAMEFLAGS
                     BYTE LIBICB$B_BLOCK_VERSION
                  end group LIBICB$R_HDR_DESC
            end variant
         end group LIBICB$R_HDR
         BASIC$QUADWORD LIBICB$ih_spare_01
         group LIBICB$r_unwind_context
            variant
               case
                  group LIBICB$r_ucontext
                     BASIC$QUADWORD LIBICB$ih_uc_flags
                     BASIC$QUADWORD LIBICB$ph_uc_link
                     group LIBICB$r_iregset
                        variant
                        case
                           group LIBICB$r_ireg  !  Dwarf numbering, ordering
                              group LIBICB$r_raxovr
                                 variant
                                 case
                                    BASIC$QUADWORD LIBICB$ih_rax  !  r0
                                 case
                                    BASIC$QUADWORD LIBICB$ih_ai  !  synonym for RAX (Argument Information register)
                                 end variant
                              end group LIBICB$r_raxovr
                              BASIC$QUADWORD LIBICB$ih_rdx  !  r1
                              BASIC$QUADWORD LIBICB$ih_rcx  !  r2
                              BASIC$QUADWORD LIBICB$ih_rbx  !  r3
                              BASIC$QUADWORD LIBICB$ih_rsi  !  r4
                              BASIC$QUADWORD LIBICB$ih_rdi  !  r5
                              group LIBICB$r_rbpovr
                                 variant
                                 case
                                    BASIC$QUADWORD LIBICB$ih_rbp  !  r6
                                 case
                                    BASIC$QUADWORD LIBICB$ih_bp  !  synonym for RBP (Frame Pointer register)
                                 end variant
                              end group LIBICB$r_rbpovr
                              group LIBICB$r_rspovr
                                 variant
                                 case
                                    BASIC$QUADWORD LIBICB$ih_rsp  !  r7
                                 case
                                    BASIC$QUADWORD LIBICB$ih_sp  !  synonym for RSP (Stack Pointer register)
                                 end variant
                              end group LIBICB$r_rspovr
                              BASIC$QUADWORD LIBICB$ih_r8
                              BASIC$QUADWORD LIBICB$ih_r9
                              BASIC$QUADWORD LIBICB$ih_r10
                              BASIC$QUADWORD LIBICB$ih_r11
                              BASIC$QUADWORD LIBICB$ih_r12
                              BASIC$QUADWORD LIBICB$ih_r13
                              BASIC$QUADWORD LIBICB$ih_r14
                              BASIC$QUADWORD LIBICB$ih_r15
                              group LIBICB$r_ripovr
                                 variant
                                 case
                                    BASIC$QUADWORD LIBICB$ih_rip  !  r16, ra, pc
                                 case
                                    BASIC$QUADWORD LIBICB$ih_ip  !  synonym for RIP (Instruction Pointer)
                                 end variant
                              end group LIBICB$r_ripovr
                              BASIC$QUADWORD LIBICB$IH_PSEUDO_REGS ( 31 )
                              BASIC$QUADWORD LIBICB$ih_rflags
                              group LIBICB$R_SEGMENT_REGISTERS
                                 variant
                                 case
                                    BASIC$QUADWORD LIBICB$ih_fsgs
                                 case
                                    group LIBICB$R_FS_GS_REGISTERS
                                       WORD LIBICB$w_fs
                                       WORD LIBICB$w_gs
                                    end group LIBICB$R_FS_GS_REGISTERS
                                 end variant
                              end group LIBICB$R_SEGMENT_REGISTERS
                              group LIBICB$R_SSE_FP_CS_REGISTERS
                                 variant
                                 case
                                    BASIC$QUADWORD LIBICB$ih_mxcsr_fcw_fsw
                                 case
                                    group LIBICB$R_SSE_FP_CSR
                                       LONG LIBICB$l_mxcsr
                                       WORD LIBICB$w_fcw
                                       WORD LIBICB$w_fsw
                                    end group LIBICB$R_SSE_FP_CSR
                                 end variant
                              end group LIBICB$R_SSE_FP_CS_REGISTERS
                           end group LIBICB$r_ireg
                        case
                           BASIC$QUADWORD LIBICB$ih_ireg ( 15 )
                        case
                           BASIC$QUADWORD LIBICB$ih_gregs ( 51 )  !  deprecated - will go away ...
                        end variant
                     end group LIBICB$r_iregset
                     group LIBICB$r_fp_save_area_addr
                        variant
                        case
                           BASIC$QUADWORD LIBICB$ph_xsave
                        case
                           BASIC$QUADWORD LIBICB$ph_fpreg  !  deprecated - will go away ...
                        case
                           BASIC$QUADWORD LIBICB$ph_fpregs  !  deprecated - will go away ...
                        end variant
                     end group LIBICB$r_fp_save_area_addr
                     BASIC$QUADWORD LIBICB$IH_XSAVE_STATE
                     LONG LIBICB$l_xsave_length
                     LONG LIBICB$l_spare_02
                     BASIC$QUADWORD LIBICB$ih_reserved1 ( 5 )
                  end group LIBICB$r_ucontext
               case
                  BASIC$QUADWORD LIBICB$ih_ucontext ( 62 )
            end variant
         end group LIBICB$r_unwind_context
         BASIC$QUADWORD LIBICB$ih_ucursor ( 127 )
         BASIC$QUADWORD LIBICB$IH_PSP       !  SP at entry to routine (Previous SP)
         BASIC$QUADWORD LIBICB$IH_PSP_VALID  !  PreviousSP valid
         group LIBICB$r_return_addr
            variant
               case
                  BASIC$QUADWORD LIBICB$IH_RETURN_IP  !  Return IP for SDA.
               case
                  BASIC$QUADWORD LIBICB$IH_RETURN_PC  !  deprecated - will go away ...
            end variant
         end group LIBICB$r_return_addr
         BASIC$QUADWORD LIBICB$PH_CHFCTX_ADDR  !  Pointer to condition handler facility context block
         BASIC$QUADWORD LIBICB$PH_OTHER     !  Pointer to other interesting structure (if any)
         BASIC$QUADWORD LIBICB$IH_OSSD      !  Copy of OSSD from Unwind Information Block
         BASIC$QUADWORD LIBICB$IH_HANDLER_PV  !  Condition Handler Procedure Value
         BASIC$QUADWORD LIBICB$PH_LSDA      !  Virtual Address of LSD area of UIB
    ! 
    !   The following locations can be used to alter the default behavior
    !   Typically this would be used for cross-process unwinding, and
    !   specifying an alternative memory allocation scheme.
         group LIBICB$r_op_flags
            variant
               case
                  LONG LIBICB$R_UO_BASE     !  base of User Override area
               case
                  BASIC$QUADWORD LIBICB$Q_UO_FLAGS  !  operational flags
               case
                  group LIBICB$r_uo_flag_bits
    !  cache unwind information between calls
    !  for effiecient stack walk.
                      !  Internal use only
                     BYTE UO_FLAG_CACHE_UNWIND_bits   ! COMMENT ADDED BY SDL - UO_FLAG_CACHE_UNWIND_bits contains bits  &
 ! UO_FLAG_CACHE_UNWIND through FILL_1_
                  end group LIBICB$r_uo_flag_bits
            end variant
         end group LIBICB$r_op_flags
         BASIC$QUADWORD LIBICB$IH_UO_IDENT  !  user context variable, passed by value
    !  to the following callback routines.
         BASIC$QUADWORD LIBICB$PH_UO_READ_MEM  !  Pointer to user "read memory" routine
         BASIC$QUADWORD LIBICB$PH_UO_GETUEINFO  !  Pointer to user "get Unwind Entry Information" routine
         BASIC$QUADWORD LIBICB$PH_UO_GETCONTEXT  !  Pointer to user "get Initial Context" routine
         BASIC$QUADWORD LIBICB$PH_UO_WRITE_MEM  !  Pointer to user "put memory" routine
         BASIC$QUADWORD LIBICB$PH_UO_WRITE_REG  !  Pointer to user "put register" routine
         BASIC$QUADWORD LIBICB$PH_UO_MALLOC  !  Pointer to user "malloc" routine
         BASIC$QUADWORD LIBICB$PH_UO_FREE   !  Pointer to user "free" routine
         BASIC$QUADWORD LIBICB$PH_UO_ACTION_ROUTINE  !  Pointer to user "action" routine - actions 
    !  are defined by "action codes" (see below).
         BASIC$QUADWORD LIBICB$ih_spare_10
    ! ******* End of User Override area ***************************
    !  the following locations are used internally, and should not be
    !  modified by the user
         BASIC$QUADWORD LIBICB$ph_most_recent_context  !  Most recent user context used
         group LIBICB$r_int_flags
            variant
               case
                  LONG LIBICB$l_internal_flags  !  internal operational flags
               case
                  group LIBICB$r_int_flag_bits
                     BYTE using_client_memread_bits   ! COMMENT ADDED BY SDL - using_client_memread_bits contains bits  &
 ! using_client_memread through FILL_2_
                  end group LIBICB$r_int_flag_bits
            end variant
         end group LIBICB$r_int_flags
         LONG LIBICB$l_interface_state      !  enum InterfaceUsageState
         LONG LIBICB$l_ip_source            !  enum IP_SOURCE
    !  The alert code can be examined to a more detailed failure status
         LONG LIBICB$L_ALERT_CODE           !  enum _UNW_ReturnCode
         BASIC$QUADWORD LIBICB$ih_spare_11
         STRING LIBICB$t_align_2 = 0
    !  The following is an "internal" area that's reserved for use by
    !  the operating system. It's size may vary over time.
         BASIC$QUADWORD LIBICB$IH_SYSTEM_DEFINED ( 1 )
    ! 
    !    Action codes are passed as the first parameter to the UO_ACTION_ROUTINE to indicate
    !    an action to be performed.  The remaining parameters to the action routine are action
    !    dependent, and usually include the ident value as the last parameter.
    ! 
    !    Action routine prototype:
    ! 
    !       uint64 return_value = action_routine (enum action_code code, ..., uint64 ident);
    ! 
    !    A return_value of ACTION_USE_DEFAULT indicates that the action was not performed
    !    and the calling standard routines should fall back to "default" processing.
    !    Other return values are action dependent.
    ! 
      end record INVO_CONTEXT_BLK
    
    !  Write Register callback routine - WhichReg enum.
    ! 
    !  The Write Register callback routine is only used when a live
    !  register in another (remote) process needs to be written as
    !  a result of a call to LIB$X86_PUT_INVO_REGISTERS.
    !  It is permissible to implement a subset of these registers,
    !  or not implement it at all if you are sure that these registers
    !  have been saved to memory before PUT_INVO is called
    ! 
    !  For the General Registers:
    !    whichReg = LIBICB$K_WhichReg_GR0 + register number
    !    value_1  = 64-bit register value
    ! 
      DECLARE LONG CONSTANT LIBICB$K_WhichReg_GR0 = 0
    ! 
    !  For the Floating Registers:
    !    whichReg = LIBICB$K_WhichReg_FR0 + floating register number
    !    value_1  = 64-bit lower floating fill value
    !    value_2  = 64-bit upper floating fill value
    ! 
      DECLARE LONG CONSTANT LIBICB$K_WhichReg_FR0 = 16
      DECLARE LONG CONSTANT LIBICB$K_WhichReg_FPSR = 24