Lists all GIF tag identifiers.
Values:
| IGMDTAG_ID_GIF_FORMAT | GIF metadata format identifier. |
| IGMDTAG_ID_GIF_HEADER | GIF header. |
| IGMDTAG_ID_GIF_HDR_SIGNATURE | Identifies the GIF Data Stream. |
| IGMDTAG_ID_GIF_HDR_VERSION | Version number. |
| IGMDTAG_ID_GIF_SCREEN_DESCRIPTOR | Logical screen descriptor. |
| IGMDTAG_ID_GIF_SCR_SCREEN_WIDTH | Logical screen width. |
| IGMDTAG_ID_GIF_SCR_SCREEN_HEIGHT | Logical screen height. |
| IGMDTAG_ID_GIF_SCR_BACKGROUND_COLOR | Background color index. |
| IGMDTAG_ID_GIF_SCR_ASPECT_RATIO | Pixel aspect ratio. |
| IGMDTAG_ID_GIF_SCR_FIELDS | Logical screen packed fields. |
| IGMDTAG_ID_GIF_SCR_FLD_GL_COLOR_TABLE | Global color table flag. |
| IGMDTAG_ID_GIF_SCR_FLD_COLOR_RES | Color resolution. |
| IGMDTAG_ID_GIF_SCR_FLD_SORT | Sort flag. |
| IGMDTAG_ID_GIF_SCR_FLD_SIZE | Global color table size. |
| IGMDTAG_ID_GIF_GLOBAL_COLOR_TABLE | Global color table. |
| IGMDTAG_ID_GIF_IMAGE_DESCRIPTOR | Image descriptor. |
| IGMDTAG_ID_GIF_IMG_LEFT_POSITION | Image left position. |
| IGMDTAG_ID_GIF_IMG_TOP_POSITION | Image top position. |
| IGMDTAG_ID_GIF_IMG_IMAGE_WIDTH | Image width. |
| IGMDTAG_ID_GIF_IMG_IMAGE_HEIGHT | Image height. |
| IGMDTAG_ID_GIF_IMG_FIELDS | Image descriptor packed field. |
| IGMDTAG_ID_GIF_IMG_FLD_LOC_COLOR_TABLE | Local color table flag. |
| IGMDTAG_ID_GIF_IMG_FLD_INTERLACE | Interlace flag. |
| IGMDTAG_ID_GIF_IMG_FLD_SORT | Sort flag. |
| IGMDTAG_ID_GIF_IMG_FLD_SIZE | Local color table size. |
| IGMDTAG_ID_GIF_LOCAL_COLOR_TABLE | Local color table. |
| IGMDTAG_ID_GIF_GRAPHIC_CONTROL_EXT | Graphic control extension. |
| IGMDTAG_ID_GIF_GCE_FIELDS | Graphic control extension packed fields. |
| IGMDTAG_ID_GIF_GCE_FLD_DISPOSAL_METHOD | Disposal method. |
| IGMDTAG_ID_GIF_GCE_FLD_USER_INPUT | User input flag. |
| IGMDTAG_ID_GIF_GCE_FLD_TRANSPARENT | Transparent color flag. |
| IGMDTAG_ID_GIF_GCE_DELAY_TIME | Delay time. |
| IGMDTAG_ID_GIF_GCE_TRANSPARENT_COLOR | Transparent color index. |
| IGMDTAG_ID_GIF_COMMENT_EXTENSION | Comment extension. |
| IGMDTAG_ID_GIF_PLAIN_TEXT_EXTENSION | Plain text extension. |
| IGMDTAG_ID_GIF_TXT_GRID_LEFT | Text grid left position. |
| IGMDTAG_ID_GIF_TXT_GRID_TOP | Text grid top position. |
| IGMDTAG_ID_GIF_TXT_GRID_WIDTH | Text grid width. |
| IGMDTAG_ID_GIF_TXT_GRID_HEIGHT | Text grid height. |
| IGMDTAG_ID_GIF_TXT_CELL_WIDTH | Character cell width. |
| IGMDTAG_ID_GIF_TXT_CELL_HEIGHT | Character cell height. |
| IGMDTAG_ID_GIF_TXT_FOREGROUND_COLOR | Text foreground color index. |
| IGMDTAG_ID_GIF_TXT_BACKGROUND_COLOR | Text background color index. |
| IGMDTAG_ID_GIF_TXT_TEXT_DATA | Plain text data. |
| IGMDTAG_ID_GIF_APP_EXTENSION | Application extension. |
| IGMDTAG_ID_GIF_APP_IDENTIFIER | Application identifier. |
| IGMDTAG_ID_GIF_APP_AUTH_CODE | Application authentication code. |
| IGMDTAG_ID_GIF_APP_DATA | Application data. |
| IGMDTAG_ID_GIF_AFTER_IMAGE_EXT | After image extensions. |