CWinApp::WinHelp

// Header File: HELPIDS.H 
// 
// This example header file is #include'd twice: 
// (1) It is #include'd by the .CPP file that passes the DWORD 
//     context i.d. to CWinApp::WinHelp. 
// (2) It is #include'd in the [MAP] section of the .HPJ file, 
//     to associate the help context string "HID_MYTOPIC" with
//     the help context numeric i.d., 101. 
// The help context string "HID_MYTOPIC" is what identifies the
// help topic in the help .RTF source file, in the "#" footnote:
//     # HID_MYTOPIC 
// 
// Note, it is not necessary to manage help context id's this way 
// for help topics associated with command id's and user interface 
// id's defined in your RESOURCE.H file; you should use the MAKEHM 
// tool via the custom build rule on your resource.h file to produce  
// a help map (.HM) file for these id's.  It is necessary to manage  
// help context id's as illustrated here only for help topics not  
// associated with command id's or user interface id's. 

#define HID_MYTOPIC 101

// Show the custom help topic that has the context string 
// "HID_MYTOPIC" in the help .RTF file, and which is mapped
// to the DWORD i.d. HID_MYTOPIC in the above HELPIDS.H file.
AfxGetApp()->WinHelp(HID_MYTOPIC);


// The following is one line of code in the help map (.HM) 
// file produced by the MAKEHM tool, which is called by the custom 
// build rule on the resource.h file.  The MAKEHM tool reads the  
// following #define in the application's RESOURCE.H file:
#define ID_MYCOMMAND 0x08004
// and adds a help id offset value of 0x10000 to create the 
// help context DWORD value 0x18004: 
// HID_MYCOMMAND                           0x18004 
// See MFC Tech Note 28 for more information on help id offset values. 

// Rarely will you need to directly call WinHelp yourself 
// with the help context i.d. for a command or user interface 
// object. The framework will call WinHelp automatically when 
// the user, for example, hits F1 when the focus is on a 
// My Command menu item. However, if you do want to directly 
// call WinHelp for the help topic associated with the command, 
// here is how you would do it:

AfxGetApp()->WinHelp(0x10000 + ID_MYCOMMAND);