#DEFINE HH_DISPLAY_TOPIC        0x0000
#DEFINE HH_HELP_FINDER          0x0000  && WinHelp equivalent
#DEFINE HH_DISPLAY_TOC          0x0001  
#DEFINE HH_DISPLAY_INDEX        0x0002  
#DEFINE HH_DISPLAY_SEARCH       0x0003  
#DEFINE HH_SET_WIN_TYPE         0x0004
#DEFINE HH_GET_WIN_TYPE         0x0005
#DEFINE HH_GET_WIN_HANDLE       0x0006
#DEFINE HH_ENUM_INFO_TYPE       0x0007  && Get Info type name, call repeatedly to enumerate, -1 at end
#DEFINE HH_SET_INFO_TYPE        0x0008  && Add Info type to filter.
#DEFINE HH_SYNC                 0x0009
#DEFINE HH_RESERVED1            0x000A
#DEFINE HH_RESERVED2            0x000B
#DEFINE HH_RESERVED3            0x000C
#DEFINE HH_KEYWORD_LOOKUP       0x000D
#DEFINE HH_DISPLAY_TEXT_POPUP   0x000E  && display string resource id or text in a popup window
#DEFINE HH_HELP_CONTEXT         0x000F  && display mapped numeric value in dwData
#DEFINE HH_TP_HELP_CONTEXTMENU  0x0010  && text popup help, same as WinHelp HELP_CONTEXTMENU
#DEFINE HH_TP_HELP_WM_HELP      0x0011  && text popup help, same as WinHelp HELP_WM_HELP
#DEFINE HH_CLOSE_ALL            0x0012  && close all windows opened directly or indirectly by the caller
#DEFINE HH_ALINK_LOOKUP         0x0013  && ALink version of HH_KEYWORD_LOOKUP
#DEFINE HH_GET_LAST_ERROR       0x0014  && not currently implemented // See HHERROR.h
#DEFINE HH_ENUM_CATEGORY        0x0015	&& Get category name, call repeatedly to enumerate, -1 at end
#DEFINE HH_ENUM_CATEGORY_IT     0x0016  && Get category info type members, call repeatedly to enumerate, -1 at end
#DEFINE HH_RESET_IT_FILTER      0x0017  && Clear the info type filter of all info types.
#DEFINE HH_SET_INCLUSIVE_FILTER 0x0018  && set inclusive filtering method for untyped topics to be included in display
#DEFINE HH_SET_EXCLUSIVE_FILTER 0x0019  && set exclusive filtering method for untyped topics to be excluded from display
#DEFINE HH_INITIALIZE           0x001C  && Initializes the help system.
#DEFINE HH_UNINITIALIZE         0x001D  && Uninitializes the help system.
#DEFINE HH_PRETRANSLATEMESSAGE  0x00fd  && Pumps messages. (NULL, NULL, MSG*). 
#DEFINE HH_SET_GLOBAL_PROPERTY  0x00fc  && Set a global property. (NULL, NULL, HH_GPROP)
