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

#ifndef  wpstyler_idl
#define  wpstyler_idl
#include <wpabs.idl>
#include <somcls.idl>

interface M_Styler;

interface Styler : WPAbstract
{
   ULONG InsertObjectStylePage(in HWND hwndDlg);
   //  Override: InsertObjectStylePage
   //
   //  Description:
   //    Insert the Styler page into the Settings notebook.

   ULONG QueryObjectStyle(in HWND hwndDlg);
   //  Override: QueryObjectStyle
   //
   //  Description:
   //    Query the object's title and current style.
   //    Set the Styler Settings page checkboxes and MLE.

   VOID  SetObjectStyle(in HWND hwndDlg);
   //  Override: SetObjectStyle
   //
   //  Description:
   //    Query the current checkbox state and set
   //    the object's style accordingly.

   #ifdef __SOMIDL__
   implementation
   {
      releaseorder: InsertObjectStylePage,QueryObjectStyle,SetObjectStyle;

      /*
       * Class modifiers
       */
      functionprefix = Sty_;
      majorversion   = 1;
      minorversion   = 2;
      filestem       = wpstyler;
      metaclass      = M_Styler;
      callstyle      = oidl;
      dllname        = "wpstyler.dll";

      /*
       * Internal instance variables
       */
      BOOL     fGeneralPage;     // Display the General page if true
      ULONG    ulStyle;          // Save the style flags
      WPObject self;             // Save the self pointer of dropped object

      /*
       * Passthru to the .IH file the following:
       */
      passthru C_ih =
      "#define INCL_PM"
      "#define INCL_DOS"
      "#define INCL_DEV"
      "#define INCL_WPCLASS"
      "#define INCL_WINWORKPLACE"

      "#include <os2.h>"
      "#include <stdlib.h>"
      "#include <string.h>"
      "#include \"wpstyler.rch\""
      "#include <somobj.h>"
      ""
      "#define OPEN_STYLER            (OPEN_USER+1)"
      ""

      "#define MPNULL                 (MPFROMP(NULL))"
      "#define MPZERO                 (MPFROMSHORT(0))"
      "#define MRTRUE                 (MRFROMSHORT((SHORT) TRUE))"
      "#define MRFALSE                (MRFROMSHORT((SHORT) FALSE))"
      ""
      "#define BM_UNCHECKED           0   // Parms in BM_SETCHECK message"
      "#define BM_CHECKED             1   // to set or clear the radio buttons"
      ""

      "#define PMWinSetDlgItemChecked(hwnd, id, bCheck)\"
      "               (WinSendDlgItemMsg((hwnd), (id), BM_SETCHECK,\"
      "               ((bCheck) ? MPFROMSHORT(1) : MPZERO), MPNULL))"
      ""
      "#define PMWinIsDlgItemChecked(hwnd, id)\"
      "               (SHORT1FROMMR(WinSendDlgItemMsg((hwnd), (id),\"
      "               BM_QUERYCHECK, MPNULL, MPNULL)) != 0)"
      ""
      "#define WinSetDialogFont(hwnd, usId, szFont)\"
      "               (WinSetPresParam(WinWindowFromID(hwnd, usId),\"
      "               PP_FONTNAMESIZE, (ULONG) strlen(szFont)+1, szFont))"
      "";

      /*
       * Method modifiers
       */
      wpInitData:                      override;
      //  Override: wpInitData
      //
      //  Description:
      //    Initialize the state variables.  Allocate any extra
      //    memory that WPStyler might need.

      wpDragOver:                      override;
      //   Method: wpDragOver
      //
      //   Description:
      //     Allow any object to be dropped on the Styler.

      wpDrop:                          override;
      //   Method: wpDrop
      //
      //   Description:
      //     Query the self pointer of dropped object.
      //     Call wpOpen to open the Settings notebook
      //     and display the styles.

      wpOpen:                          override;
      //   Method: wpOpen
      //
      //   Description:
      //     Opens the Settings notebook to display the General page
      //     for the Styler object.

      wpAddSettingsPages:              override;
      //   Method: wpAddSettingsPages
      //
      //   Description:
      //     Add the Styler Settings page to let the user alter
      //     the styles of any object that is dropped onto us.

      wpAddObjectWindowPage:           override;
      //   Method: wpAddObjectWindowPage
      //
      //   Description:
      //     Remove the Window page.

      wpAddObjectGeneralPage:           override;
      //   Method: wpAddObjectGeneralPage
      //
      //   Description:
      //     Remove the General page when the Styler
      //     page is displayed.

   };
   #endif /* __SOMIDL__ */
};

interface M_Styler : M_WPAbstract
{
   HMODULE clsQueryModuleHandle();
   //   Method: clsQueryModuleHandle
   //
   //   Description:
   //     Return the module handle.


   #ifdef __SOMIDL__
   implementation
   {
      releaseorder: clsQueryModuleHandle;

      /*
       * Class modifiers
       */
      functionprefix = StyM_;
      majorversion   = 1;
      minorversion   = 2;
      filestem       = wpstyler;
      callstyle      = oidl;
      dllname        = "wpstyler.dll";

      /*
       * Internal instance variables
       */
      HMODULE  hmod;    /* Resource module handle */
      HPOINTER hicon;   /* Icon handle            */

      /*
       * Method modifiers
       */

      wpclsInitData:                   override;
      //   Method: wpclsInitData
      //
      //   Description:
      //     Initalize the class data, query and save the module handle.
      //     Load the icon handle.

      wpclsQueryIcon:                  override;
      //   Method: wpclsQueryIcon
      //
      //   Description:
      //     Set the Stylers icon handle.

      wpclsQueryStyle:                 override;
      //   Method: wpclsQueryStyle
      //
      //   Description:
      //     wpclsQueryStyle is called to allow the class object to
      //     specify the default object class style for its instances.
      //
      //   Remarks:
      //     This method can be called at any time in order to determine the
      //     default style for instances of this class.
      //     This method should be overridden in order to modify the default
      //     object style for instances of this class.

      wpclsQueryDefaultHelp:           override;
      //   Method: wpclsQueryDefaultHelp
      //
      //   Description:
      //     Set the help library name and default help ID.

      wpclsQueryDefaultView:           override;
      //   Method: wpclsQueryDefaultView
      //
      //   Description:
      //     Return the default view for a new instance of this object.
      //     Tell the system what the Styler's default view is.
   };
   #endif /* __SOMIDL__ */
};
#endif  /* wpstyler_idl */