Use at your own discretion. Feel free to add new sections as you see fit, as long as you maintain the same format.

/boot/develop/headers/be/app/AppDefs.h

• B_ABOUT_REQUESTED = '_ABR'
• B_WINDOW_ACTIVATED = '_ACT'
• B_APP_ACTIVATED = '_ACT' (Same as B_WINDOW_ACTIVATED)
• B_ARGV_RECEIVED = '_ARG'
• B_QUIT_REQUESTED = '_QRQ'
• B_CLOSE_REQUESTED = '_QRQ' (Obsolete use B_QUIT_REQUESTED)
• B_CANCEL = '_CNC'
• B_KEY_DOWN = '_KYD'
• B_KEY_UP = '_KYU'
• B_UNMAPPED_KEY_DOWN = '_UKD'
• B_UNMAPPED_KEY_UP = '_UKU'
• B_MODIFIERS_CHANGED = '_MCH'
• B_MINIMIZE = '_WMN'
• B_MOUSE_DOWN = '_MDN'
• B_MOUSE_MOVED = '_MMV'
• B_MOUSE_ENTER_EXIT = '_MEX'
• B_MOUSE_UP = '_MUP'
• B_MOUSE_WHEEL_CHANGED = '_MWC'
• B_OPEN_IN_WORKSPACE = '_OWS'
• B_PRINTER_CHANGED = '_PCH'
• B_PULSE = '_PUL'
• B_READY_TO_RUN = '_RTR'
• B_REFS_RECEIVED = '_RRC'
• B_RELEASE_OVERLAY_LOCK = '_ROV'
• B_ACQUIRE_OVERLAY_LOCK = '_AOV'
• B_SCREEN_CHANGED = '_SCH'
• B_VALUE_CHANGED = '_VCH'
• B_VIEW_MOVED = '_VMV'
• B_VIEW_RESIZED = '_VRS'
• B_WINDOW_MOVED = '_WMV'
• B_WINDOW_RESIZED = '_WRS'
• B_WORKSPACES_CHANGED = '_WCG'
• B_WORKSPACE_ACTIVATED = '_WAC'
• B_ZOOM = '_WZM'
• _APP_MENU_ = '_AMN'
• _BROWSER_MENUS_ = '_BRM'
• _MENU_EVENT_ = '_MEV'
• _PING_ = '_PBL'
• _QUIT_ = '_QIT'
• _VOLUME_MOUNTED_ = '_NVL'
• _VOLUME_UNMOUNTED_ = '_VRM'
• _MESSAGE_DROPPED_ = '_MDP'
• _DISPOSE_DRAG_ = '_DPD'
• _MENUS_DONE_ = '_MND'
• _SHOW_DRAG_HANDLES_ = '_SDH'
• _EVENTS_PENDING_ = '_EVP'
• _UPDATE_ = '_UPD'
• _UPDATE_IF_NEEDED_ = '_UPN'
• _PRINTER_INFO_ = '_PIN'
• _SETUP_PRINTER_ = '_SUP'
• _SELECT_PRINTER_ = '_PSL'
• B_SET_PROPERTY = 'PSET'
• B_GET_PROPERTY = 'PGET'
• B_CREATE_PROPERTY = 'PCRT'
• B_DELETE_PROPERTY = 'PDEL'
• B_COUNT_PROPERTIES = 'PCNT'
• B_EXECUTE_PROPERTY = 'PEXE'
• B_GET_SUPPORTED_SUITES = 'SUIT'
• B_UNDO = 'UNDO'
• B_CUT = 'CCUT'
• B_COPY = 'COPY'
• B_PASTE = 'PSTE'
• B_SELECT_ALL = 'SALL'
• B_SAVE_REQUESTED = 'SAVE'
• B_MESSAGE_NOT_UNDERSTOOD = 'MNOT'
• B_NO_REPLY = 'NONE'
• B_REPLY = 'RPLY'
• B_SIMPLE_DATA = 'DATA'
• B_MIME_DATA = 'MIME'
• B_ARCHIVED_OBJECT = 'ARCV'
• B_UPDATE_STATUS_BAR = 'SBUP'
• B_RESET_STATUS_BAR = 'SBRS'
• B_NODE_MONITOR = 'NDMN'
• B_QUERY_UPDATE = 'QUPD'
• B_ENDORSABLE = 'ENDO'
• B_COPY_TARGET = 'DDCP'
• B_MOVE_TARGET = 'DDMV'
• B_TRASH_TARGET = 'DDRM'
• B_LINK_TARGET = 'DDLN'
• B_INPUT_DEVICES_CHANGED = 'IDCH'
• B_INPUT_METHOD_EVENT = 'IMEV'
• B_WINDOW_MOVE_TO = 'WDMT'
• B_WINDOW_MOVE_BY = 'WDMB'
• B_SILENT_RELAUNCH = 'AREL'
• B_OBSERVER_NOTICE_CHANGE = 'NTCH'
• B_CONTROL_INVOKED = 'CIVK'
• B_CONTROL_MODIFIED = 'CMOD'

/boot/develop/headers/be/app/Clipboard.h

• B_CLIPBOARD_CHANGED = 'CLCH'

/boot/develop/headers/be/app/PropertyInfo.h

• B_PROPERTY_INFO_TYPE 'SCTD'

/boot/develop/headers/be/app/Roster.h

• B_SOME_APP_LAUNCHED = 'BRAS'
• B_SOME_APP_QUIT = 'BRAQ'
• B_SOME_APP_ACTIVATED = 'BRAW'

/boot/develop/headers/be/be_apps/NetPositive/NetPositive.h

• B_NETPOSITIVE_OPEN_URL = 'NPOP'
• B_NETPOSITIVE_BACK = 'NPBK'
• B_NETPOSITIVE_FORWARD = 'NPFW'
• B_NETPOSITIVE_HOME = 'NPHM'
• B_NETPOSITIVE_RELOAD = 'NPRL'
• B_NETPOSITIVE_STOP = 'NPST'
• B_NETPOSITIVE_DOWN = 'NPDN'
• B_NETPOSITIVE_UP = 'NPUP'

/boot/develop/headers/be/be_apps/Tracker/Background.h

• const int32 B_RESTORE_BACKGROUND_IMAGE = 'Tbgr' (force a Tracker window to use a new background image)

/boot/develop/headers/be/device/atomizer_driver.h

• ATOMIZER_PRIVATE_DATA_MAGIC 'ATOM' (a private driver rev of sorts)

/boot/develop/headers/be/interface/OptionControl.h

• B_OPTION_CONTROL_VALUE = '_BMV'

/boot/develop/headers/be/media/MediaDefs.h

• B_MEDIA_WILDCARD = 'TRWC' (used to match any notification in Start/StopWatching)
• B_MEDIA_NODE_CREATED = 'TRIA' ("media_node_id" (multiple items)
• B_SEEK_TAG = 'TRST' (user data type of the codec seek
• B_TIME_CODE = 'TRTC' (user data is media_header_time_code

/boot/develop/headers/be/media/MediaNode.h

• B_NODE_FAILED_START = 'TRI0'

/boot/develop/headers/be/media/ParameterWeb.h

• B_MEDIA_PARAMETER_TYPE = 'BMCT'
• B_MEDIA_PARAMETER_WEB_TYPE = 'BMCW'
• B_MEDIA_PARAMETER_GROUP_TYPE= 'BMCG'

/boot/develop/headers/be/midi2/MidiRoster.h

• B_MIDI_EVENT 'MIDI'

/boot/develop/headers/be/storage/Mime.h

• static const uint32 B_MIME_STRING_TYPE = 'MIMS'
• B_META_MIME_CHANGED = 'MMCH'

/boot/develop/headers/be/storage/ResourceStrings.h

• RESOURCE_TYPE = 'CSTR'

/boot/develop/headers/be/support/TypeConstants.h

• B_ANY_TYPE = 'ANYT'
• B_BOOL_TYPE = 'BOOL'
• B_CHAR_TYPE = 'CHAR'
• B_COLOR_8_BIT_TYPE = 'CLRB'
• B_DOUBLE_TYPE = 'DBLE'
• B_FLOAT_TYPE = 'FLOT'
• B_GRAYSCALE_8_BIT_TYPE = 'GRYB'
• B_INT64_TYPE = 'LLNG'
• B_INT32_TYPE = 'LONG'
• B_INT16_TYPE = 'SHRT'
• B_INT8_TYPE = 'BYTE'
• B_MESSAGE_TYPE = 'MSGG'
• B_MESSENGER_TYPE = 'MSNG'
• B_MIME_TYPE = 'MIME'
• B_MONOCHROME_1_BIT_TYPE = 'MNOB'
• B_OBJECT_TYPE = 'OPTR'
• B_OFF_T_TYPE = 'OFFT'
• B_PATTERN_TYPE = 'PATN'
• B_POINTER_TYPE = 'PNTR'
• B_POINT_TYPE = 'BPNT'
• B_RAW_TYPE = 'RAWT'
• B_RECT_TYPE = 'RECT'
• B_REF_TYPE = 'RREF'
• B_RGB_32_BIT_TYPE = 'RGBB'
• B_RGB_COLOR_TYPE = 'RGBC'
• B_SIZE_T_TYPE = 'SIZT'
• B_SSIZE_T_TYPE = 'SSZT'
• B_STRING_TYPE = 'CSTR'
• B_TIME_TYPE = 'TIME'
• B_UINT64_TYPE = 'ULLG'
• B_UINT32_TYPE = 'ULNG'
• B_UINT16_TYPE = 'USHT'
• B_UINT8_TYPE = 'UBYT'
• B_MEDIA_PARAMETER_TYPE = 'BMCT'
• B_MEDIA_PARAMETER_WEB_TYPE = 'BMCW'
• B_MEDIA_PARAMETER_GROUP_TYPE= 'BMCG'
• B_ASCII_TYPE = 'TEXT' (use B_STRING_TYPE instead)
• _DEPRECATED_TYPE_1_ = 'PATH'

/boot/develop/headers/be/translation/TranslationUtils.h

• B_TRANSLATION_MENU = 'BTMN'

/boot/develop/headers/be/translation/TranslatorFormats.h

• B_TRANSLATOR_BITMAP = 'bits' (TranslatorBitmap)
• B_TRANSLATOR_PICTURE = 'pict' (BPicture data)
• B_TRANSLATOR_TEXT = 'TEXT' (B_ASCII_TYPE)
• B_TRANSLATOR_SOUND = 'nois' (TranslatorSound)
• B_TRANSLATOR_MIDI = 'midi' (standard MIDI)
• B_TRANSLATOR_MEDIA = 'mhi!' (a stream of stuff)
• B_TRANSLATOR_NONE = 'none'
• B_GIF_FORMAT = 'GIF '
• B_JPEG_FORMAT = 'JPEG'
• B_PNG_FORMAT = 'PNG '
• B_PPM_FORMAT = 'PPM '
• B_TGA_FORMAT = 'TGA '
• B_BMP_FORMAT = 'BMP '
• B_TIFF_FORMAT = 'TIFF'
• B_DXF_FORMAT = 'DXF '
• B_EPS_FORMAT = 'EPS '
• B_PICT_FORMAT = 'PICT' (MacOS PICT file)
• B_WAV_FORMAT = 'WAV '
• B_AIFF_FORMAT = 'AIFF'
• B_CD_FORMAT = 'CD ' (44 kHz stereo 16 bit linear big-endian)
• B_AU_FORMAT = 'AU ' (Sun ulaw)
• B_STYLED_TEXT_FORMAT = 'STXT'
• STREAM_HEADER_MAGIC = 'STXT'
• TEXT_HEADER_MAGIC = 'TEXT'
• STYLE_HEADER_MAGIC = 'STYL'