OPTITEM

using System;
using System.Runtime.InteropServices;

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct OPTITEM
{
    public ushort cbSize;
    public byte Level;
    public byte DlgPageIdx;
    public uint Flags;
    public UIntPtr UserData;
    public IntPtr pName;
    public _Anonymous1_e__Union Anonymous1;
    public _Anonymous2_e__Union Anonymous2;
    public IntPtr pOptType;
    public uint HelpIndex;
    public byte DMPubID;
    public byte UserItemID;
    public ushort wReserved;
    public IntPtr pOIExt;
    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)] public UIntPtr[] dwReserved;
}

Imports System.Runtime.InteropServices

<StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Unicode)>
Public Structure OPTITEM
    Public cbSize As UShort
    Public Level As Byte
    Public DlgPageIdx As Byte
    Public Flags As UInteger
    Public UserData As UIntPtr
    Public pName As IntPtr
    Public Anonymous1 As _Anonymous1_e__Union
    Public Anonymous2 As _Anonymous2_e__Union
    Public pOptType As IntPtr
    Public HelpIndex As UInteger
    Public DMPubID As Byte
    Public UserItemID As Byte
    Public wReserved As UShort
    Public pOIExt As IntPtr
    <MarshalAs(UnmanagedType.ByValArray, SizeConst:=3)> Public dwReserved() As UIntPtr
End Structure

import ctypes
from ctypes import wintypes

class OPTITEM(ctypes.Structure):
    _fields_ = [
        ("cbSize", ctypes.c_ushort),
        ("Level", ctypes.c_ubyte),
        ("DlgPageIdx", ctypes.c_ubyte),
        ("Flags", wintypes.DWORD),
        ("UserData", ctypes.c_size_t),
        ("pName", ctypes.c_void_p),
        ("Anonymous1", _Anonymous1_e__Union),
        ("Anonymous2", _Anonymous2_e__Union),
        ("pOptType", ctypes.c_void_p),
        ("HelpIndex", wintypes.DWORD),
        ("DMPubID", ctypes.c_ubyte),
        ("UserItemID", ctypes.c_ubyte),
        ("wReserved", ctypes.c_ushort),
        ("pOIExt", ctypes.c_void_p),
        ("dwReserved", ctypes.c_size_t * 3),
    ]

#[repr(C)]
pub struct OPTITEM {
    pub cbSize: u16,
    pub Level: u8,
    pub DlgPageIdx: u8,
    pub Flags: u32,
    pub UserData: usize,
    pub pName: *mut core::ffi::c_void,
    pub Anonymous1: _Anonymous1_e__Union,
    pub Anonymous2: _Anonymous2_e__Union,
    pub pOptType: *mut core::ffi::c_void,
    pub HelpIndex: u32,
    pub DMPubID: u8,
    pub UserItemID: u8,
    pub wReserved: u16,
    pub pOIExt: *mut core::ffi::c_void,
    pub dwReserved: [usize; 3],
}

import "golang.org/x/sys/windows"

type OPTITEM struct {
	cbSize uint16
	Level byte
	DlgPageIdx byte
	Flags uint32
	UserData uintptr
	pName uintptr
	Anonymous1 _Anonymous1_e__Union
	Anonymous2 _Anonymous2_e__Union
	pOptType uintptr
	HelpIndex uint32
	DMPubID byte
	UserItemID byte
	wReserved uint16
	pOIExt uintptr
	dwReserved [3]uintptr
}

type
  OPTITEM = record
    cbSize: Word;
    Level: Byte;
    DlgPageIdx: Byte;
    Flags: DWORD;
    UserData: NativeUInt;
    pName: Pointer;
    Anonymous1: _Anonymous1_e__Union;
    Anonymous2: _Anonymous2_e__Union;
    pOptType: Pointer;
    HelpIndex: DWORD;
    DMPubID: Byte;
    UserItemID: Byte;
    wReserved: Word;
    pOIExt: Pointer;
    dwReserved: array[0..2] of NativeUInt;
  end;

const OPTITEM = extern struct {
    cbSize: u16,
    Level: u8,
    DlgPageIdx: u8,
    Flags: u32,
    UserData: usize,
    pName: ?*anyopaque,
    Anonymous1: _Anonymous1_e__Union,
    Anonymous2: _Anonymous2_e__Union,
    pOptType: ?*anyopaque,
    HelpIndex: u32,
    DMPubID: u8,
    UserItemID: u8,
    wReserved: u16,
    pOIExt: ?*anyopaque,
    dwReserved: [3]usize,
};

type
  OPTITEM {.bycopy.} = object
    cbSize: uint16
    Level: uint8
    DlgPageIdx: uint8
    Flags: uint32
    UserData: uint
    pName: pointer
    Anonymous1: _Anonymous1_e__Union
    Anonymous2: _Anonymous2_e__Union
    pOptType: pointer
    HelpIndex: uint32
    DMPubID: uint8
    UserItemID: uint8
    wReserved: uint16
    pOIExt: pointer
    dwReserved: array[3, uint]

struct OPTITEM
{
    ushort cbSize;
    ubyte Level;
    ubyte DlgPageIdx;
    uint Flags;
    size_t UserData;
    void* pName;
    _Anonymous1_e__Union Anonymous1;
    _Anonymous2_e__Union Anonymous2;
    void* pOptType;
    uint HelpIndex;
    ubyte DMPubID;
    ubyte UserItemID;
    ushort wReserved;
    void* pOIExt;
    size_t[3] dwReserved;
}