The following sample illustrates the class interface definition file (IDL):

//# Include the class definition file for the parent classes

#include <wpdataf.idl>
#include <somcls.idl>

interface M_Hello;   // Forward reference to metaclass

//#******************************************************************************
//#   Define the new class
//#******************************************************************************

interface Hello : WPDataFile
{
//
// CLASS: Hello
//
// CLASS HIERARCHY:
//
//     SOMObject
//       ÀÄÄÄWPObject
//             ÀÄÄÄWPFileSystem
//                   ÀÄÄÄWPDataFile
//                         ÀÄÄÄHello
//
// DESCRIPTION:
//
//    This is the sample class to demonstrate Workplace Shell menu
//    customization.
//
#ifdef __SOMIDL__
implementation
{
    //# Class modifiers
    externalstem   = hello;
    local;
    externalprefix = hlo_;
    majorversion   = 1;
    minorversion   = 2;

    filestem       = hello;
    metaclass      = M_Hello;
    callstyle      = idl;
    dllname        = "hello.dll";

    passthru C_h   =  ""
    "#define INCL_WIN"
    "#include <os2.h>"
    ""
    "/*"
    " *   The following user-defined pop-up menu items (ID_xxx) should"
    " *   be higher than WPMENUID_USER."
    " *"
    " *   The ID_OPENHELLO will become a submenu of the system's pop-up"
    " *   open menu id, WPMENUID_OPEN."
    " */"
    ""
    "#define ID_OPENHELLO   (WPMENUID_USER+1)  /* Menus to be added  */"
    "#define ID_MSGBOX      (WPMENUID_USER+2)"
    "#define IDM_OPENHELLO  (WPMENUID_USER+3)  /* Submenus of added menus */"
    "#define IDM_MSGBOX     (WPMENUID_USER+4)"
    "#define ID_FRAME       3000               /* Hello window frame ID */"
    ""
    "// The ID of the Hello window view. This is returned by the override"
    "// of wpclsQueryDefaultView to specify that the default view"
    "// is to open the Hello window. This ID MUST be the same as the ID of"
    "// the open menu item."
    ""
    "#define OPEN_HELLO     ID_OPENHELLO";

//#******************************************************************************
//#   Define overridden methods
//#******************************************************************************

    wpFilterPopupMenu: override;

// METHOD: wpFilterPopupMenu
//
// DESCRIPTION: Remove any menu items from the context
//              menu that don't apply.
//
// HOW TO OVERRIDE: No restrictions.
//
// NOTES:
//
//   This method is called when an objects' context menu has been requested
//   (i.e. right click or S-F10 on an object) before displaying the menu. It
//   is called before wpModifyPopupMenu.

    wpModifyPopupMenu: override;

// METHOD: wpModifyPopupMenu
//
// DESCRIPTION:  Add the menu items to the context menu.
//
// NOTES:
//
//   This method is called when an objects' context menu has been requested
//   (i.e. right click or S-F10 on an object) before displaying the menu. It
//   is called after wpFilterPopupMenu.

    wpMenuItemSelected: override;

// METHOD: wpMenuItemSelected
//
// DESCRIPTION: Processes input from the menu options that was added.
//
// NOTES:
//
//   This method is called when an item in an objects' context menu has been
//   selected.

    wpOpen: override;

// METHOD: wpOpen
//
// DESCRIPTION: Opens the Hello Workplace Shell window.
//
// NOTES:
//
//   This method is called when a new open view of an object is needed,
//   i.e. when an item in an object's Open submenu has been selected or
//   when an object is double clicked on.  This is equivalent to selecting
//   the default item in the object's Open submenu.
//
//   wpOpen should always open a new view. The Workplace Shell actually calls
//   wpViewObject first when an object is double clicked on or an open
//   submenu item is selected. wpViewObject will then call wpOpen if there
//   is currently no open view of the selected Open submenu item or if
//   mutliple concurrent views of the object are enabled.

};   /* End implementation */
#Endif /* __SOMIDL__ */
};

//#******************************************************************************
//#   Define the metaclass
//#******************************************************************************

interface M_Hello: M_WPDataFile
{

//#******************************************************************************
//#   Define metaclass methods
//#******************************************************************************

   HMODULE  clsQueryModuleHandle();

// METHOD: clsQueryModuleHandle
//
// DESCRIPTION:
//
//   Returns the module handle of this class.  If this is the
//   first invocation, DosQueryModuleHandle is called to save the handle
//   for future invocations.
//
// RETURN:
//
//   0              Unsuccessful
//   non-zero       Module handle
//
// NOTES:
//
//   This method is called when a new open view of an object is needed,
//   i.e. when an item in an object's Open submenu has been selected or
//   when an object is double clicked on.  This is equivalent to selecting
//   the default item in the object's Open submenu.
//

//#******************************************************************************
//#   Define metaclass data
//#******************************************************************************

   attribute HMODULE hmod;

#ifdef __SOMIDL__
implementation
{
    releaseorder: clsQueryModuleHandle;

    //# Class modifiers
    externalstem   = hello;
    local;
    externalprefix = hloM_;
    majorversion   = 1;
    minorversion   = 2;
    filestem       = hello;
    callstyle      = oidl;
    dllname        = "hello.dll";

//#******************************************************************************
//#   Define overridden metaclass methods
//#******************************************************************************

   wpclsQueryDefaultView: override;

// METHOD: wpclsQueryDefaultView
//
// DESCRIPTION: Returns the default view for a new instance
//              of this object.
//
// REMARKS:
//
//   Return the ID of the default view, OPEN_HELLO.
//   This ID must be the same as the ID of the open
//   submenu item, ID_OPENHELLO.
//
// NOTES:
//
//   This method is called to determine which view to open when an
//   object of class Hello is double clicked on.

   wpclsQueryTitle: override;

// METHOD: wpclsQueryTitle
//
// DESCRIPTION:  Return the string "Hello Workplace Shell".
//
// NOTES:
//
//   This method is called by the Workplace Shell to determine the object
//   title when an object of class Hello is created.
//
  }; /* End implementation */
#endif /* __SOMIDL__ */
};