/* exif-tag.c
 *
 * Copyright (c) 2001 Lutz Mueller <lutz@users.sourceforge.net>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, 
 * but WITHOUT ANY WARRANTY; without even the implied warranty of 
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details. 
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA  02110-1301  USA.
 *
 * SPDX-License-Identifier: LGPL-2.0-or-later
 */

#include <config.h>

#include <libexif/exif-tag.h>
#include <libexif/i18n.h>

#include <stdlib.h>
#include <string.h>

#define ESL_NNNN { EXIF_SUPPORT_LEVEL_NOT_RECORDED, EXIF_SUPPORT_LEVEL_NOT_RECORDED, EXIF_SUPPORT_LEVEL_NOT_RECORDED, EXIF_SUPPORT_LEVEL_NOT_RECORDED }
#define ESL_OOOO { EXIF_SUPPORT_LEVEL_OPTIONAL, EXIF_SUPPORT_LEVEL_OPTIONAL, EXIF_SUPPORT_LEVEL_OPTIONAL, EXIF_SUPPORT_LEVEL_OPTIONAL }
#define ESL_MMMN { EXIF_SUPPORT_LEVEL_MANDATORY, EXIF_SUPPORT_LEVEL_MANDATORY, EXIF_SUPPORT_LEVEL_MANDATORY, EXIF_SUPPORT_LEVEL_NOT_RECORDED }
#define ESL_MMMM { EXIF_SUPPORT_LEVEL_MANDATORY, EXIF_SUPPORT_LEVEL_MANDATORY, EXIF_SUPPORT_LEVEL_MANDATORY, EXIF_SUPPORT_LEVEL_MANDATORY }
#define ESL_OMON { EXIF_SUPPORT_LEVEL_OPTIONAL, EXIF_SUPPORT_LEVEL_MANDATORY, EXIF_SUPPORT_LEVEL_OPTIONAL, EXIF_SUPPORT_LEVEL_NOT_RECORDED }
#define ESL_NNOO { EXIF_SUPPORT_LEVEL_NOT_RECORDED, EXIF_SUPPORT_LEVEL_NOT_RECORDED, EXIF_SUPPORT_LEVEL_OPTIONAL, EXIF_SUPPORT_LEVEL_OPTIONAL }
#define ESL_NNMN { EXIF_SUPPORT_LEVEL_NOT_RECORDED, EXIF_SUPPORT_LEVEL_NOT_RECORDED, EXIF_SUPPORT_LEVEL_MANDATORY, EXIF_SUPPORT_LEVEL_NOT_RECORDED }
#define ESL_NNMM { EXIF_SUPPORT_LEVEL_NOT_RECORDED, EXIF_SUPPORT_LEVEL_NOT_RECORDED, EXIF_SUPPORT_LEVEL_MANDATORY, EXIF_SUPPORT_LEVEL_MANDATORY }
#define ESL_NNNM { EXIF_SUPPORT_LEVEL_NOT_RECORDED, EXIF_SUPPORT_LEVEL_NOT_RECORDED, EXIF_SUPPORT_LEVEL_NOT_RECORDED, EXIF_SUPPORT_LEVEL_MANDATORY }
#define ESL_NNNO { EXIF_SUPPORT_LEVEL_NOT_RECORDED, EXIF_SUPPORT_LEVEL_NOT_RECORDED, EXIF_SUPPORT_LEVEL_NOT_RECORDED, EXIF_SUPPORT_LEVEL_OPTIONAL }
#define ESL_UUUU { EXIF_SUPPORT_LEVEL_UNKNOWN, EXIF_SUPPORT_LEVEL_UNKNOWN, EXIF_SUPPORT_LEVEL_UNKNOWN, EXIF_SUPPORT_LEVEL_UNKNOWN }
#define ESL_GPS { ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN }
#define ESL_UNKNOWN { ESL_UUUU, ESL_UUUU, ESL_UUUU, ESL_UUUU, ESL_UUUU }

/*!
 * Table giving information about each EXIF tag.
 * There may be more than one entry with the same tag value because some tags
 * have different meanings depending on the IFD in which they appear.
 * When there are such duplicate entries, there must be no overlap in their
 * support levels.
 * The entries MUST be sorted in tag order.
 * The name and title are mandatory, but the description may be an empty
 * string. None of the entries may be NULL except the final array terminator.
 */
static const struct TagEntry {
	/*! Tag ID. There may be duplicate tags when the same number is used for
	 * different meanings in different IFDs. */
	ExifTag tag;
	const char *name;
	const char *title;
	const char *description;
	/*! indexed by the types [ExifIfd][ExifDataType] */
	ExifSupportLevel esl[EXIF_IFD_COUNT][EXIF_DATA_TYPE_COUNT];
} ExifTagTable[] = {
#ifndef NO_VERBOSE_TAG_STRINGS
	{EXIF_TAG_GPS_VERSION_ID, "GPSVersionID", N_("GPS Tag Version"),
	 N_("Indicates the version of <GPSInfoIFD>. The version is given "
	    "as 2.0.0.0. This tag is mandatory when <GPSInfo> tag is "
	    "present. (Note: The <GPSVersionID> tag is given in bytes, "
	    "unlike the <ExifVersion> tag. When the version is "
	    "2.0.0.0, the tag value is 02000000.H)."), ESL_GPS},
	{EXIF_TAG_INTEROPERABILITY_INDEX, "InteroperabilityIndex",
	 N_("Interoperability Index"),
	 N_("Indicates the identification of the Interoperability rule. "
	    "Use \"R98\" for stating ExifR98 Rules. Four bytes used "
	    "including the termination code (NULL). see the separate "
	    "volume of Recommended Exif Interoperability Rules (ExifR98) "
	    "for other tags used for ExifR98."),
	 { ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_OOOO } },
	{EXIF_TAG_GPS_LATITUDE_REF, "GPSLatitudeRef", N_("North or South Latitude"),
	 N_("Indicates whether the latitude is north or south latitude. The "
	    "ASCII value 'N' indicates north latitude, and 'S' is south "
	    "latitude."), ESL_GPS},
	{EXIF_TAG_INTEROPERABILITY_VERSION, "InteroperabilityVersion",
	 N_("Interoperability Version"), "",
	 { ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_OOOO } },
	{EXIF_TAG_GPS_LATITUDE, "GPSLatitude", N_("Latitude"),
	 N_("Indicates the latitude. The latitude is expressed as three "
	    "RATIONAL values giving the degrees, minutes, and seconds, "
	    "respectively. When degrees, minutes and seconds are expressed, "
	    "the format is dd/1,mm/1,ss/1. When degrees and minutes are used "
	    "and, for example, fractions of minutes are given up to two "
	    "decimal places, the format is dd/1,mmmm/100,0/1."),
	 ESL_GPS},
	{EXIF_TAG_GPS_LONGITUDE_REF, "GPSLongitudeRef", N_("East or West Longitude"),
	 N_("Indicates whether the longitude is east or west longitude. "
	    "ASCII 'E' indicates east longitude, and 'W' is west "
	    "longitude."), ESL_GPS},
	{EXIF_TAG_GPS_LONGITUDE, "GPSLongitude", N_("Longitude"),
	 N_("Indicates the longitude. The longitude is expressed as three "
	    "RATIONAL values giving the degrees, minutes, and seconds, "
	    "respectively. When degrees, minutes and seconds are expressed, "
	    "the format is ddd/1,mm/1,ss/1. When degrees and minutes are "
	    "used and, for example, fractions of minutes are given up to "
	    "two decimal places, the format is ddd/1,mmmm/100,0/1."),
	 ESL_GPS},
	{EXIF_TAG_GPS_ALTITUDE_REF, "GPSAltitudeRef", N_("Altitude Reference"),
	 N_("Indicates the altitude used as the reference altitude. If the "
	    "reference is sea level and the altitude is above sea level, 0 "
	    "is given. If the altitude is below sea level, a value of 1 is given "
	    "and the altitude is indicated as an absolute value in the "
	    "GPSAltitude tag. The reference unit is meters. Note that this tag "
	    "is BYTE type, unlike other reference tags."), ESL_GPS},
	{EXIF_TAG_GPS_ALTITUDE, "GPSAltitude", N_("Altitude"),
	 N_("Indicates the altitude based on the reference in GPSAltitudeRef. "
	    "Altitude is expressed as one RATIONAL value. The reference unit "
	    "is meters."), ESL_GPS},
	{EXIF_TAG_GPS_TIME_STAMP, "GPSTimeStamp", N_("GPS Time (Atomic Clock)"),
         N_("Indicates the time as UTC (Coordinated Universal Time). "
	    "TimeStamp is expressed as three RATIONAL values giving "
            "the hour, minute, and second."), ESL_GPS},
	{EXIF_TAG_GPS_SATELLITES, "GPSSatellites", N_("GPS Satellites"),
         N_("Indicates the GPS satellites used for measurements. This "
            "tag can be used to describe the number of satellites, their ID "
            "number, angle of elevation, azimuth, SNR and other information "
            "in ASCII notation. The format is not specified. If the GPS "
            "receiver is incapable of taking measurements, value of the tag "
            "shall be set to NULL."), ESL_GPS},
	{EXIF_TAG_GPS_STATUS, "GPSStatus", N_("GPS Receiver Status"),
         N_("Indicates the status of the GPS receiver when the image is "
            "recorded. 'A' means measurement is in progress, and 'V' means "
            "the measurement is Interoperability."), ESL_GPS},
	{EXIF_TAG_GPS_MEASURE_MODE, "GPSMeasureMode", N_("GPS Measurement Mode"),
         N_("Indicates the GPS measurement mode. '2' means "
            "two-dimensional measurement and '3' means three-dimensional "
            "measurement is in progress."), ESL_GPS},
	{EXIF_TAG_GPS_DOP, "GPSDOP", N_("Measurement Precision"),
         N_("Indicates the GPS DOP (data degree of precision). An HDOP "
            "value is written during two-dimensional measurement, and PDOP "
            "during three-dimensional measurement."), ESL_GPS},
	{EXIF_TAG_GPS_SPEED_REF, "GPSSpeedRef", N_("Speed Unit"),
         N_("Indicates the unit used to express the GPS receiver speed "
            "of movement. 'K', 'M' and 'N' represent kilometers per hour, "
            "miles per hour, and knots."), ESL_GPS},
	{EXIF_TAG_GPS_SPEED, "GPSSpeed", N_("Speed of GPS Receiver"),
	 N_("Indicates the speed of GPS receiver movement."), ESL_GPS},
	{EXIF_TAG_GPS_TRACK_REF, "GPSTrackRef", N_("Reference for direction of movement"),
         N_("Indicates the reference for giving the direction of GPS "
            "receiver movement. 'T' denotes true direction and 'M' is "
            "magnetic direction."), ESL_GPS},
	{EXIF_TAG_GPS_TRACK, "GPSTrack", N_("Direction of Movement"),
         N_("Indicates the direction of GPS receiver movement. The range "
            "of values is from 0.00 to 359.99."), ESL_GPS},
	{EXIF_TAG_GPS_IMG_DIRECTION_REF, "GPSImgDirectionRef", N_("GPS Image Direction Reference"),
	 N_("Indicates the reference for giving the direction of the image when it is captured. "
	    "'T' denotes true direction and 'M' is magnetic direction."), ESL_GPS},
	{EXIF_TAG_GPS_IMG_DIRECTION, "GPSImgDirection", N_("GPS Image Direction"),
	 N_("Indicates the direction of the image when it was captured. The range of values is "
	    "from 0.00 to 359.99."), ESL_GPS},
	{EXIF_TAG_GPS_MAP_DATUM, "GPSMapDatum", N_("Geodetic Survey Data Used"),
         N_("Indicates the geodetic survey data used by the GPS "
            "receiver. If the survey data is restricted to Japan, the value "
            "of this tag is 'TOKYO' or 'WGS-84'. If a GPS Info tag is "
            "recorded, it is strongly recommended that this tag be recorded."), ESL_GPS},
	{EXIF_TAG_GPS_DEST_LATITUDE_REF, "GPSDestLatitudeRef", N_("Reference For Latitude of Destination"),
         N_("Indicates whether the latitude of the destination point is "
            "north or south latitude. The ASCII value 'N' indicates north "
            "latitude, and 'S' is south latitude."), ESL_GPS},
	{EXIF_TAG_GPS_DEST_LATITUDE, "GPSDestLatitude", N_("Latitude of Destination"),
         N_("Indicates the latitude of the destination point. The "
            "latitude is expressed as three RATIONAL values giving the "
            "degrees, minutes, and seconds, respectively. If latitude is "
            "expressed as degrees, minutes and seconds, a typical format "
            "would be dd/1,mm/1,ss/1. When degrees and minutes are used and, "
            "for example, fractions of minutes are given up to two decimal "
            "places, the format would be dd/1,mmmm/100,0/1."), ESL_GPS},
	{EXIF_TAG_GPS_DEST_LONGITUDE_REF, "GPSDestLongitudeRef", N_("Reference for Longitude of Destination"),
         N_("Indicates whether the longitude of the destination point is "
            "east or west longitude. ASCII 'E' indicates east longitude, and "
            "'W' is west longitude."), ESL_GPS},
	{EXIF_TAG_GPS_DEST_LONGITUDE, "GPSDestLongitude", N_("Longitude of Destination"),
         N_("Indicates the longitude of the destination point. The "
            "longitude is expressed as three RATIONAL values giving the "
            "degrees, minutes, and seconds, respectively. If longitude is "
            "expressed as degrees, minutes and seconds, a typical format "
            "would be ddd/1,mm/1,ss/1. When degrees and minutes are used "
            "and, for example, fractions of minutes are given up to two "
            "decimal places, the format would be ddd/1,mmmm/100,0/1."),
         ESL_GPS},
	{EXIF_TAG_GPS_DEST_BEARING_REF, "GPSDestBearingRef", N_("Reference for Bearing of Destination"),
         N_("Indicates the reference used for giving the bearing to "
            "the destination point. 'T' denotes true direction and 'M' is "
            "magnetic direction."), ESL_GPS},
	{EXIF_TAG_GPS_DEST_BEARING, "GPSDestBearing", N_("Bearing of Destination"),
         N_("Indicates the bearing to the destination point. The range "
            "of values is from 0.00 to 359.99."), ESL_GPS},
	{EXIF_TAG_GPS_DEST_DISTANCE_REF, "GPSDestDistanceRef", N_("Reference for Distance to Destination"),
         N_("Indicates the unit used to express the distance to the "
            "destination point. 'K', 'M' and 'N' represent kilometers, miles "
            "and nautical miles."), ESL_GPS},
	{EXIF_TAG_GPS_DEST_DISTANCE, "GPSDestDistance", N_("Distance to Destination"),
	 N_("Indicates the distance to the destination point."), ESL_GPS},
	{EXIF_TAG_GPS_PROCESSING_METHOD, "GPSProcessingMethod", N_("Name of GPS Processing Method"),
         N_("A character string recording the name of the method used "
            "for location finding. The first byte indicates the character "
            "code used, and this is followed by the name "
            "of the method. Since the Type is not ASCII, NULL termination is "
            "not necessary."), ESL_GPS},
	{EXIF_TAG_GPS_AREA_INFORMATION, "GPSAreaInformation", N_("Name of GPS Area"),
         N_("A character string recording the name of the GPS area. The "
            "first byte indicates the character code used, "
            "and this is followed by the name of the GPS area. Since "
            "the Type is not ASCII, NULL termination is not necessary."), ESL_GPS},
	{EXIF_TAG_GPS_DATE_STAMP, "GPSDateStamp", N_("GPS Date"),
         N_("A character string recording date and time information "
            "relative to UTC (Coordinated Universal Time). The format is "
            "\"YYYY:MM:DD\". The length of the string is 11 bytes including "
            "NULL."), ESL_GPS},
	{EXIF_TAG_GPS_DIFFERENTIAL, "GPSDifferential", N_("GPS Differential Correction"),
         N_("Indicates whether differential correction is applied to the "
            "GPS receiver."), ESL_GPS},
	{EXIF_TAG_GPS_H_POSITIONING_ERROR, "GPSHPositioningError", N_("GPS Horizontal Positioning Error"),
         N_("Indicates the horizontal positioning errors in meters. This is "
            "expressed as one RATIONAL value."), ESL_GPS},
	/* Not in EXIF 2.2 */
	{EXIF_TAG_NEW_SUBFILE_TYPE, "NewSubfileType",
	 N_("New Subfile Type"), N_("A general indication of the kind of data "
	    "contained in this subfile."),
	 ESL_UNKNOWN},
	{EXIF_TAG_IMAGE_WIDTH, "ImageWidth", N_("Image Width"),
	 N_("The number of columns of image data, equal to the number of "
	    "pixels per row. In JPEG compressed data a JPEG marker is "
	    "used instead of this tag."),
	 { ESL_MMMN, ESL_MMMN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_IMAGE_LENGTH, "ImageLength", N_("Image Length"),
	 N_("The number of rows of image data. In JPEG compressed data a "
	    "JPEG marker is used instead of this tag."), 
	 { ESL_MMMN, ESL_MMMN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_BITS_PER_SAMPLE, "BitsPerSample", N_("Bits per Sample"),
	 N_("The number of bits per image component. In this standard each "
	    "component of the image is 8 bits, so the value for this "
	    "tag is 8. See also <SamplesPerPixel>. In JPEG compressed data "
	    "a JPEG marker is used instead of this tag."),
	 { ESL_MMMN, ESL_MMMN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_COMPRESSION, "Compression", N_("Compression"),
	 N_("The compression scheme used for the image data. When a "
	    "primary image is JPEG compressed, this designation is "
	    "not necessary and is omitted. When thumbnails use JPEG "
	    "compression, this tag value is set to 6."),
	 { ESL_MMMN, ESL_MMMM, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_PHOTOMETRIC_INTERPRETATION, "PhotometricInterpretation",
	 N_("Photometric Interpretation"),
	 N_("The pixel composition. In JPEG compressed data a JPEG "
	    "marker is used instead of this tag."),
	 { ESL_MMMN, ESL_MMMN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	/* Not in EXIF 2.2 */
	{EXIF_TAG_FILL_ORDER, "FillOrder", N_("Fill Order"), "", ESL_UNKNOWN},
	/* Not in EXIF 2.2 */
	{EXIF_TAG_DOCUMENT_NAME, "DocumentName", N_("Document Name"), "",
	 ESL_UNKNOWN},
	{EXIF_TAG_IMAGE_DESCRIPTION, "ImageDescription",
	 N_("Image Description"),
	 N_("A character string giving the title of the image. It may be "
	    "a comment such as \"1988 company picnic\" or "
	    "the like. Two-bytes character codes cannot be used. "
	    "When a 2-bytes code is necessary, the Exif Private tag "
	    "<UserComment> is to be used."),
	 { ESL_OOOO, ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_MAKE, "Make", N_("Manufacturer"),
	 N_("The manufacturer of the recording "
	    "equipment. This is the manufacturer of the DSC, scanner, "
	    "video digitizer or other equipment that generated the "
	    "image. When the field is left blank, it is treated as "
	    "unknown."),
	 { ESL_OOOO, ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_MODEL, "Model", N_("Model"),
	 N_("The model name or model number of the equipment. This is the "
	    "model name or number of the DSC, scanner, video digitizer "
	    "or other equipment that generated the image. When the field "
	    "is left blank, it is treated as unknown."),
	 { ESL_OOOO, ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_STRIP_OFFSETS, "StripOffsets", N_("Strip Offsets"),
	 N_("For each strip, the byte offset of that strip. It is "
	    "recommended that this be selected so the number of strip "
	    "bytes does not exceed 64 Kbytes. With JPEG compressed "
	    "data this designation is not needed and is omitted. See also "
	    "<RowsPerStrip> and <StripByteCounts>."),
	 { ESL_MMMN, ESL_MMMN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_ORIENTATION, "Orientation", N_("Orientation"),
	 N_("The image orientation viewed in terms of rows and columns."),
	 { ESL_OOOO, ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_SAMPLES_PER_PIXEL, "SamplesPerPixel",
	 N_("Samples per Pixel"),
	 N_("The number of components per pixel. Since this standard applies "
	    "to RGB and YCbCr images, the value set for this tag is 3. "
	    "In JPEG compressed data a JPEG marker is used instead of this "
	    "tag."), 
	 { ESL_MMMN, ESL_MMMN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_ROWS_PER_STRIP, "RowsPerStrip", N_("Rows per Strip"),
	 N_("The number of rows per strip. This is the number of rows "
	    "in the image of one strip when an image is divided into "
	    "strips. With JPEG compressed data this designation is not "
	    "needed and is omitted. See also <StripOffsets> and "
	    "<StripByteCounts>."),
	 { ESL_MMMN, ESL_MMMN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_STRIP_BYTE_COUNTS, "StripByteCounts", N_("Strip Byte Count"),
	 N_("The total number of bytes in each strip. With JPEG compressed "
	    "data this designation is not needed and is omitted."),
	 { ESL_MMMN, ESL_MMMN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_X_RESOLUTION, "XResolution", N_("X-Resolution"),
	 N_("The number of pixels per <ResolutionUnit> in the <ImageWidth> "
	    "direction. When the image resolution is unknown, 72 [dpi] "
	    "is designated."),
	 { ESL_MMMM, ESL_MMMM, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_Y_RESOLUTION, "YResolution", N_("Y-Resolution"),
	 N_("The number of pixels per <ResolutionUnit> in the <ImageLength> "
	    "direction. The same value as <XResolution> is designated."),
	 { ESL_MMMM, ESL_MMMM, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_PLANAR_CONFIGURATION, "PlanarConfiguration",
	 N_("Planar Configuration"),
	 N_("Indicates whether pixel components are recorded in a chunky "
	    "or planar format. In JPEG compressed files a JPEG marker "
	    "is used instead of this tag. If this field does not exist, "
	    "the TIFF default of 1 (chunky) is assumed."),
	 { ESL_OMON, ESL_OMON, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_RESOLUTION_UNIT, "ResolutionUnit", N_("Resolution Unit"),
	 N_("The unit for measuring <XResolution> and <YResolution>. The same "
	    "unit is used for both <XResolution> and <YResolution>. If "
	    "the image resolution is unknown, 2 (inches) is designated."),
	 { ESL_MMMM, ESL_MMMM, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_TRANSFER_FUNCTION, "TransferFunction",
	 N_("Transfer Function"),
	 N_("A transfer function for the image, described in tabular style. "
	    "Normally this tag is not necessary, since color space is "
	    "specified in the color space information tag (<ColorSpace>)."),
	 { ESL_OOOO, ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_SOFTWARE, "Software", N_("Software"),
	 N_("This tag records the name and version of the software or "
	    "firmware of the camera or image input device used to "
	    "generate the image. The detailed format is not specified, but "
	    "it is recommended that the example shown below be "
	    "followed. When the field is left blank, it is treated as "
	    "unknown."),
	 { ESL_OOOO, ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_DATE_TIME, "DateTime", N_("Date and Time"),
	 N_("The date and time of image creation. In this standard "
	    "(EXIF-2.1) it is the date and time the file was changed."),
	 { ESL_OOOO, ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_ARTIST, "Artist", N_("Artist"),
	 N_("This tag records the name of the camera owner, photographer or "
	    "image creator. The detailed format is not specified, but it is "
	    "recommended that the information be written as in the example "
	    "below for ease of Interoperability. When the field is "
	    "left blank, it is treated as unknown."),
	 { ESL_OOOO, ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_WHITE_POINT, "WhitePoint", N_("White Point"),
	 N_("The chromaticity of the white point of the image. Normally "
	    "this tag is not necessary, since color space is specified "
	    "in the color space information tag (<ColorSpace>)."),
	 { ESL_OOOO, ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_PRIMARY_CHROMATICITIES, "PrimaryChromaticities",
	 N_("Primary Chromaticities"),
	 N_("The chromaticity of the three primary colors of the image. "
	    "Normally this tag is not necessary, since color space is "
	    "specified in the color space information tag (<ColorSpace>)."),
	 { ESL_OOOO, ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	/* Not in EXIF 2.2 */
	{EXIF_TAG_SUB_IFDS, "SubIFDs", "SubIFD Offsets", N_("Defined by Adobe Corporation "
	    "to enable TIFF Trees within a TIFF file."), ESL_UNKNOWN},
	/* Not in EXIF 2.2 */
	{EXIF_TAG_TRANSFER_RANGE, "TransferRange", N_("Transfer Range"), "",
	 ESL_UNKNOWN},
	/* Not in EXIF 2.2 */
	{EXIF_TAG_JPEG_PROC, "JPEGProc", "JPEGProc", "", ESL_UNKNOWN},
	{EXIF_TAG_JPEG_INTERCHANGE_FORMAT, "JPEGInterchangeFormat",
	 N_("JPEG Interchange Format"),
	 N_("The offset to the start byte (SOI) of JPEG compressed "
	    "thumbnail data. This is not used for primary image "
	    "JPEG data."),
	 { ESL_NNNN, ESL_NNNM, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_JPEG_INTERCHANGE_FORMAT_LENGTH,
	 "JPEGInterchangeFormatLength", N_("JPEG Interchange Format Length"),
	 N_("The number of bytes of JPEG compressed thumbnail data. This "
	    "is not used for primary image JPEG data. JPEG thumbnails "
	    "are not divided but are recorded as a continuous JPEG "
	    "bitstream from SOI to EOI. Appn and COM markers should "
	    "not be recorded. Compressed thumbnails must be recorded in no "
	    "more than 64 Kbytes, including all other data to be "
	    "recorded in APP1."),
	 { ESL_NNNN, ESL_NNNM, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_YCBCR_COEFFICIENTS, "YCbCrCoefficients",
	 N_("YCbCr Coefficients"),
	 N_("The matrix coefficients for transformation from RGB to YCbCr "
	    "image data. No default is given in TIFF; but here the "
	    "value given in \"Color Space Guidelines\", is used "
	    "as the default. The color space is declared in a "
	    "color space information tag, with the default being the value "
	    "that gives the optimal image characteristics "
	    "Interoperability this condition."),
	 { ESL_NNOO, ESL_NNOO, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_YCBCR_SUB_SAMPLING, "YCbCrSubSampling",
	 N_("YCbCr Sub-Sampling"),
	 N_("The sampling ratio of chrominance components in relation to the "
	    "luminance component. In JPEG compressed data a JPEG marker "
	    "is used instead of this tag."),
	 { ESL_NNMN, ESL_NNMN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_YCBCR_POSITIONING, "YCbCrPositioning",
	 N_("YCbCr Positioning"),
	 N_("The position of chrominance components in relation to the "
	    "luminance component. This field is designated only for "
	    "JPEG compressed data or uncompressed YCbCr data. The TIFF "
	    "default is 1 (centered); but when Y:Cb:Cr = 4:2:2 it is "
	    "recommended in this standard that 2 (co-sited) be used to "
	    "record data, in order to improve the image quality when viewed "
	    "on TV systems. When this field does not exist, the reader shall "
	    "assume the TIFF default. In the case of Y:Cb:Cr = 4:2:0, the "
	    "TIFF default (centered) is recommended. If the reader "
	    "does not have the capability of supporting both kinds of "
	    "<YCbCrPositioning>, it shall follow the TIFF default regardless "
	    "of the value in this field. It is preferable that readers "
	    "be able to support both centered and co-sited positioning."),
	 { ESL_NNMM, ESL_NNOO, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_REFERENCE_BLACK_WHITE, "ReferenceBlackWhite",
	 N_("Reference Black/White"),
	 N_("The reference black point value and reference white point "
	    "value. No defaults are given in TIFF, but the values "
	    "below are given as defaults here. The color space is declared "
	    "in a color space information tag, with the default "
	    "being the value that gives the optimal image characteristics "
	    "Interoperability these conditions."),
	 { ESL_OOOO, ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	/* Not in EXIF 2.2 */
	{EXIF_TAG_XML_PACKET, "XMLPacket", N_("XML Packet"), N_("XMP Metadata"),
	 ESL_UNKNOWN},
	/* Not in EXIF 2.2 */
	{EXIF_TAG_RELATED_IMAGE_FILE_FORMAT, "RelatedImageFileFormat",
	 "RelatedImageFileFormat", "", ESL_UNKNOWN},
	/* Not in EXIF 2.2 */
	{EXIF_TAG_RELATED_IMAGE_WIDTH, "RelatedImageWidth",
	 "RelatedImageWidth", "", ESL_UNKNOWN},
	/* Not in EXIF 2.2 */
	{EXIF_TAG_RELATED_IMAGE_LENGTH, "RelatedImageLength",
	 "RelatedImageLength", "", ESL_UNKNOWN},
	{EXIF_TAG_IMAGE_DEPTH, "ImageDepth",
	 "ImageDepth", "", ESL_UNKNOWN},
	/* Not in EXIF 2.2 */
	{EXIF_TAG_CFA_REPEAT_PATTERN_DIM, "CFARepeatPatternDim",
	 "CFARepeatPatternDim", "", ESL_UNKNOWN},
	/* Not in EXIF 2.2 */
	{EXIF_TAG_CFA_PATTERN, "CFAPattern",
	 N_("CFA Pattern"),
	 N_("Indicates the color filter array (CFA) geometric pattern of the "
	    "image sensor when a one-chip color area sensor is used. "
	    "It does not apply to all sensing methods."), ESL_UNKNOWN},
	/* Not in EXIF 2.2 */
	{EXIF_TAG_BATTERY_LEVEL, "BatteryLevel", N_("Battery Level"), "",
	 ESL_UNKNOWN},
	{EXIF_TAG_COPYRIGHT, "Copyright", N_("Copyright"),
	 N_("Copyright information. In this standard the tag is used to "
	    "indicate both the photographer and editor copyrights. It is "
	    "the copyright notice of the person or organization claiming "
	    "rights to the image. The Interoperability copyright "
	    "statement including date and rights should be written in this "
	    "field; e.g., \"Copyright, John Smith, 19xx. All rights "
	    "reserved.\". In this standard the field records both the "
	    "photographer and editor copyrights, with each recorded in a "
	    "separate part of the statement. When there is a clear "
	    "distinction between the photographer and editor copyrights, "
	    "these are to be written in the order of photographer followed "
	    "by editor copyright, separated by NULL (in this case, "
	    "since the statement also ends with a NULL, there are two NULL "
	    "codes) (see example 1). When only the photographer is given, "
	    "it is terminated by one NULL code (see example 2). When only "
	    "the editor copyright is given, "
	    "the photographer copyright part consists of one space followed "
	    "by a terminating NULL code, then the editor copyright is given "
	    "(see example 3). When the field is left blank, it is treated "
	    "as unknown."),
	 { ESL_OOOO, ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_EXPOSURE_TIME, "ExposureTime", N_("Exposure Time"),
	 N_("Exposure time, given in seconds (sec)."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_FNUMBER, "FNumber", N_("F-Number"),
	 N_("The F number."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	/* Not in EXIF 2.2 */
	{EXIF_TAG_IPTC_NAA, "IPTC/NAA", "IPTC/NAA", "", ESL_UNKNOWN},
	/* Not in EXIF 2.2 */
	{EXIF_TAG_IMAGE_RESOURCES, "ImageResources", N_("Image Resources Block"), "",
	 ESL_UNKNOWN},
	{EXIF_TAG_EXIF_IFD_POINTER, "ExifIfdPointer", N_("Exif IFD Pointer"),
	 N_("A pointer to the Exif IFD. Interoperability, Exif IFD has the "
	    "same structure as that of the IFD specified in TIFF. "
	    "ordinarily, however, it does not contain image data as in "
	    "the case of TIFF."),
	 { ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	/* Not in EXIF 2.2 */
	{EXIF_TAG_INTER_COLOR_PROFILE, "InterColorProfile",
	 "InterColorProfile", "", ESL_UNKNOWN},
	{EXIF_TAG_EXPOSURE_PROGRAM, "ExposureProgram", N_("Exposure Program"),
	 N_("The class of the program used by the camera to set exposure "
	    "when the picture is taken."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_SPECTRAL_SENSITIVITY, "SpectralSensitivity",
	 N_("Spectral Sensitivity"),
	 N_("Indicates the spectral sensitivity of each channel of the "
	    "camera used. The tag value is an ASCII string compatible "
	    "with the standard developed by the ASTM Technical Committee."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_GPS_INFO_IFD_POINTER, "GPSInfoIFDPointer", 
	 N_("GPS Info IFD Pointer"),
	 N_("A pointer to the GPS Info IFD. The "
	    "Interoperability structure of the GPS Info IFD, like that of "
	    "Exif IFD, has no image data."),
	 { ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_ISO_SPEED_RATINGS, "ISOSpeedRatings",
	 N_("ISO Speed Ratings"),
	 N_("Indicates the ISO Speed and ISO Latitude of the camera or "
	    "input device as specified in ISO 12232."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_OECF, "OECF", N_("Opto-Electronic Conversion Function"),
	 N_("Indicates the Opto-Electronic Conversion Function (OECF) "
	    "specified in ISO 14524. <OECF> is the relationship between "
	    "the camera optical input and the image values."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	/* Not in EXIF 2.2 */
	{EXIF_TAG_TIME_ZONE_OFFSET, "TimeZoneOffset", N_("Time Zone Offset"),
	 N_("Encodes time zone of camera clock relative to GMT."),
	 ESL_UNKNOWN},
	{EXIF_TAG_SENSITIVITY_TYPE, "SensitivityType", N_("Sensitivity Type"),
	 N_("The SensitivityType tag indicates which one of the parameters of "
	 	"ISO12232 is the PhotographicSensitivity tag. Although it is an optional "
		"tag, it should be recorded when a PhotographicSensitivity tag is recorded. "
		"Value = 4, 5, 6, or 7 may be used in case that the values of plural parameters "
		"are the same."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_STANDARD_OUTPUT_SENSITIVITY, "StandardOutputSensitivity", N_("Standard Output Sensitivity"),
	 "",
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_RECOMMENDED_EXPOSURE_INDEX, "RecommendedExposureIndex",
	 N_("Recommended Exposure Index"),
	 "",
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_ISO_SPEED, "ISOSpeed",
	 N_("ISO Speed"),
	 "",
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_ISO_SPEEDLatitudeYYY, "ISOSpeedLatitudeyyy",
	 N_("ISO Speed Latitude yyy"),
	 "",
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_ISO_SPEEDLatitudeZZZ, "ISOSpeedLatitudezzz",
	 N_("ISO Speed Latitude zzz"),
	 "",
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_EXIF_VERSION, "ExifVersion", N_("Exif Version"),
	 N_("The version of this standard supported. Nonexistence of this "
	    "field is taken to mean nonconformance to the standard."),
	 { ESL_NNNN, ESL_NNNN, ESL_MMMM, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_DATE_TIME_ORIGINAL, "DateTimeOriginal",
	 N_("Date and Time (Original)"),
	 N_("The date and time when the original image data was generated. "
	    "For a digital still camera "
	    "the date and time the picture was taken are recorded."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_DATE_TIME_DIGITIZED, "DateTimeDigitized",
	 N_("Date and Time (Digitized)"),
	 N_("The date and time when the image was stored as digital data."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	/* EXIF 2.32 */
	{EXIF_TAG_OFFSET_TIME, "OffsetTime", N_("Offset Time For DateTime"),
	 N_("A tag used to record the offset from UTC (the time difference from Universal Time Coordinated including daylight saving time) of the time of DateTime tag. The format when recording the offset is \"+|-HH:MM\". The part of \"+|-\" shall be recorded as \"+\" or \"-\". When the offset are unknown, all the character spaces except colons (\":\")should be filled with blank characters, or else the Interoperability field should be filled with blank characters. The character string length is 7 Bytes including NULL for termination. When the field is left blank, it is treated as unknown."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	/* EXIF 2.32 */
	{EXIF_TAG_OFFSET_TIME_ORIGINAL, "OffsetTimeOriginal", N_("Offset Time For DateTimeOriginal"),
	 N_("A tag used to record the offset from UTC (the time difference from Universal Time Coordinated including daylight saving  time)  of  the time  of  DateTimeOriginal  tag.  The  format  when  recording  the  offset  is \"+|-HH:MM\". The part of \"+|-\" shall be recorded as \"+\" or \"-\". When the offset are unknown, all the character spaces except colons (\":\")should be filled with blank characters, or else the Interoperability field should be filled with blank characters. The character string length is 7 Bytes including NULL for termination. When the field is left blank, it is treated as unknown."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	/* EXIF 2.32 */
	{EXIF_TAG_OFFSET_TIME_DIGITIZED, "OffsetTimeDigitized", N_("Offset Time For DateTimeDigitized"),
	 N_("A tag used to record the offset from UTC (the time difference from Universal Time Coordinated including daylight  saving  time)  of  the time  of  DateTimeDigitized  tag.  The  format  when  recording  the  offset  is \"+|-HH:MM\". The part of \"+|-\" shall be recorded as \"+\" or \"-\". When the offset are unknown, all the character spaces except colons (\":\")should be filled with blank characters, or else the Interoperability field should be filled with blank characters. The character string length is 7 Bytes including NULL for termination. When the field is left blank, it is treated as unknown."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_COMPONENTS_CONFIGURATION, "ComponentsConfiguration",
	 N_("Components Configuration"),
	 N_("Information specific to compressed data. The channels of "
	    "each component are arranged in order from the 1st "
	    "component to the 4th. For uncompressed data the data "
	    "arrangement is given in the <PhotometricInterpretation> tag. "
	    "However, since <PhotometricInterpretation> can only "
	    "express the order of Y, Cb and Cr, this tag is provided "
	    "for cases when compressed data uses components other than "
	    "Y, Cb, and Cr and to enable support of other sequences."),
	 { ESL_NNNN, ESL_NNNN, ESL_NNNM, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_COMPRESSED_BITS_PER_PIXEL, "CompressedBitsPerPixel",
	 N_("Compressed Bits per Pixel"),
	 N_("Information specific to compressed data. The compression mode "
	    "used for a compressed image is indicated in unit bits "
	    "per pixel."),
	 { ESL_NNNN, ESL_NNNN, ESL_NNNO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_SHUTTER_SPEED_VALUE, "ShutterSpeedValue", N_("Shutter Speed"),
	 N_("Shutter speed. The unit is the APEX (Additive System of "
	    "Photographic Exposure) setting."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_APERTURE_VALUE, "ApertureValue", N_("Aperture"),
	 N_("The lens aperture. The unit is the APEX value."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_BRIGHTNESS_VALUE, "BrightnessValue", N_("Brightness"),
	 N_("The value of brightness. The unit is the APEX value. "
	    "Ordinarily it is given in the range of -99.99 to 99.99."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_EXPOSURE_BIAS_VALUE, "ExposureBiasValue",
	 N_("Exposure Bias"),
	 N_("The exposure bias. The units is the APEX value. Ordinarily "
	    "it is given in the range of -99.99 to 99.99."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_MAX_APERTURE_VALUE, "MaxApertureValue", N_("Maximum Aperture Value"),
	 N_("The smallest F number of the lens. The unit is the APEX value. "
	    "Ordinarily it is given in the range of 00.00 to 99.99, "
	    "but it is not limited to this range."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_SUBJECT_DISTANCE, "SubjectDistance",
	 N_("Subject Distance"),
	 N_("The distance to the subject, given in meters."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_METERING_MODE, "MeteringMode", N_("Metering Mode"),
	 N_("The metering mode."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_LIGHT_SOURCE, "LightSource", N_("Light Source"),
	 N_("The kind of light source."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_FLASH, "Flash", N_("Flash"),
	 N_("This tag is recorded when an image is taken using a strobe "
	    "light (flash)."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_FOCAL_LENGTH, "FocalLength", N_("Focal Length"),
	 N_("The actual focal length of the lens, in mm. Conversion is not "
	    "made to the focal length of a 35 mm film camera."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_SUBJECT_AREA, "SubjectArea", N_("Subject Area"),
	 N_("This tag indicates the location and area of the main subject "
	    "in the overall scene."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	/* Not in EXIF 2.2 */
	{EXIF_TAG_TIFF_EP_STANDARD_ID, "TIFF/EPStandardID", N_("TIFF/EP Standard ID"), "",
	 ESL_UNKNOWN},
	{EXIF_TAG_MAKER_NOTE, "MakerNote", N_("Maker Note"),
	 N_("A tag for manufacturers of Exif writers to record any desired "
	    "information. The contents are up to the manufacturer."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_USER_COMMENT, "UserComment", N_("User Comment"),
	 N_("A tag for Exif users to write keywords or comments on the image "
	    "besides those in <ImageDescription>, and without the "
	    "character code limitations of the <ImageDescription> tag. The "
	    "character code used in the <UserComment> tag is identified "
	    "based on an ID code in a fixed 8-byte area at the start of "
	    "the tag data area. The unused portion of the area is padded "
	    "with NULL (\"00.h\"). ID codes are assigned by means of "
	    "registration. The designation method and references for each "
	    "character code are defined in the specification. The value of "
	    "CountN is determined based on the 8 bytes in the character code "
	    "area and the number of bytes in the user comment part. Since "
	    "the TYPE is not ASCII, NULL termination is not necessary. "
	    "The ID code for the <UserComment> area may be a Defined code "
	    "such as JIS or ASCII, or may be Undefined. The Undefined name "
	    "is UndefinedText, and the ID code is filled with 8 bytes of all "
	    "\"NULL\" (\"00.H\"). An Exif reader that reads the "
	    "<UserComment> tag must have a function for determining the "
	    "ID code. This function is not required in Exif readers that "
	    "do not use the <UserComment> tag. "
	    "When a <UserComment> area is set aside, it is recommended that "
	    "the ID code be ASCII and that the following user comment "
	    "part be filled with blank characters [20.H]."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_SUB_SEC_TIME, "SubsecTime", N_("Sub-second Time"),
	 N_("A tag used to record fractions of seconds for the "
	    "<DateTime> tag."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_SUB_SEC_TIME_ORIGINAL, "SubSecTimeOriginal",
	 N_("Sub-second Time (Original)"),
	 N_("A tag used to record fractions of seconds for the "
	    "<DateTimeOriginal> tag."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_SUB_SEC_TIME_DIGITIZED, "SubSecTimeDigitized",
	 N_("Sub-second Time (Digitized)"),
	 N_("A tag used to record fractions of seconds for the "
	    "<DateTimeDigitized> tag."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	/* Not in EXIF 2.2 (Microsoft extension) */
	{EXIF_TAG_XP_TITLE, "XPTitle", N_("XP Title"),
	 N_("A character string giving the title of the image, encoded in "
	    "UTF-16LE."),
	 { ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	/* Not in EXIF 2.2 (Microsoft extension) */
	{EXIF_TAG_XP_COMMENT, "XPComment", N_("XP Comment"), 
	 N_("A character string containing a comment about the image, encoded "
	    "in UTF-16LE."),
	 { ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	/* Not in EXIF 2.2 (Microsoft extension) */
	{EXIF_TAG_XP_AUTHOR, "XPAuthor", N_("XP Author"), 
	 N_("A character string containing the name of the image creator, "
	    "encoded in UTF-16LE."),
	 { ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	/* Not in EXIF 2.2 (Microsoft extension) */
	{EXIF_TAG_XP_KEYWORDS, "XPKeywords", N_("XP Keywords"), 
	 N_("A character string containing key words describing the image, "
	    "encoded in UTF-16LE."),
	 { ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	/* Not in EXIF 2.2 (Microsoft extension) */
	{EXIF_TAG_XP_SUBJECT, "XPSubject", N_("XP Subject"), 
	 N_("A character string giving the image subject, encoded in "
	    "UTF-16LE."),
	 { ESL_OOOO, ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_FLASH_PIX_VERSION, "FlashpixVersion", "FlashPixVersion",
	 N_("The FlashPix format version supported by a FPXR file."),
	 { ESL_NNNN, ESL_NNNN, ESL_MMMM, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_COLOR_SPACE, "ColorSpace", N_("Color Space"),
	 N_("The color space information tag is always "
	    "recorded as the color space specifier. Normally sRGB (=1) "
	    "is used to define the color space based on the PC monitor "
	    "conditions and environment. If a color space other than "
	    "sRGB is used, Uncalibrated (=FFFF.H) is set. Image data "
	    "recorded as Uncalibrated can be treated as sRGB when it is "
	    "converted to FlashPix."),
	 { ESL_NNNN, ESL_NNNN, ESL_MMMM, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_PIXEL_X_DIMENSION, "PixelXDimension", N_("Pixel X Dimension"),
	 N_("Information specific to compressed data. When a "
	    "compressed file is recorded, the valid width of the "
	    "meaningful image must be recorded in this tag, whether or "
	    "not there is padding data or a restart marker. This tag "
	    "should not exist in an uncompressed file."),
	 { ESL_NNNN, ESL_NNNN, ESL_NNNM, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_PIXEL_Y_DIMENSION, "PixelYDimension", N_("Pixel Y Dimension"),
	 N_("Information specific to compressed data. When a compressed "
	    "file is recorded, the valid height of the meaningful image "
	    "must be recorded in this tag, whether or not there is padding "
	    "data or a restart marker. This tag should not exist in an "
	    "uncompressed file. "
	    "Since data padding is unnecessary in the vertical direction, "
	    "the number of lines recorded in this valid image height tag "
	    "will in fact be the same as that recorded in the SOF."),
	 { ESL_NNNN, ESL_NNNN, ESL_NNNM, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_RELATED_SOUND_FILE, "RelatedSoundFile",
	 N_("Related Sound File"),
	 N_("This tag is used to record the name of an audio file related "
	    "to the image data. The only relational information "
	    "recorded here is the Exif audio file name and extension (an "
	    "ASCII string consisting of 8 characters + '.' + 3 "
	    "characters). The path is not recorded. Stipulations on audio "
	    "and file naming conventions are defined in the specification. "
	    "When using this tag, audio files must be recorded in "
	    "conformance to the Exif audio format. Writers are also allowed "
	    "to store the data such as Audio within APP2 as FlashPix "
	    "extension stream data. "
	    "The mapping of Exif image files and audio files is done "
	    "in any of three ways, [1], [2] and [3]. If multiple files "
	    "are mapped to one file as in [2] or [3], the above "
	    "format is used to record just one audio file name. If "
	    "there are multiple audio files, the first recorded file is "
	    "given. In the case of [3], for example, for the "
	    "Exif image file \"DSC00001.JPG\" only  \"SND00001.WAV\" is "
	    "given as the related Exif audio file. When there are three "
	    "Exif audio files \"SND00001.WAV\", \"SND00002.WAV\" and "
	    "\"SND00003.WAV\", the Exif image file name for each of them, "
	    "\"DSC00001.JPG\", is indicated. By combining multiple "
	    "relational information, a variety of playback possibilities "
	    "can be supported. The method of using relational information "
	    "is left to the implementation on the playback side. Since this "
	    "information is an ASCII character string, it is terminated by "
	    "NULL. When this tag is used to map audio files, the relation "
	    "of the audio file to image data must also be indicated on the "
	    "audio file end."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_INTEROPERABILITY_IFD_POINTER, "InteroperabilityIFDPointer",
	 N_("Interoperability IFD Pointer"),
	 N_("Interoperability IFD is composed of tags which stores the "
	    "information to ensure the Interoperability and pointed "
	    "by the following tag located in Exif IFD. "
	    "The Interoperability structure of Interoperability IFD is "
	    "the same as TIFF defined IFD structure "
	    "but does not contain the "
	    "image data characteristically compared with normal TIFF "
	    "IFD."),
	 { ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_FLASH_ENERGY, "FlashEnergy", N_("Flash Energy"),
	 N_("Indicates the strobe energy at the time the image is "
	    "captured, as measured in Beam Candle Power Seconds (BCPS)."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_SPATIAL_FREQUENCY_RESPONSE, "SpatialFrequencyResponse",
	 N_("Spatial Frequency Response"),
	 N_("This tag records the camera or input device spatial frequency "
	    "table and SFR values in the direction of image width, "
	    "image height, and diagonal direction, as specified in ISO "
	    "12233."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_FOCAL_PLANE_X_RESOLUTION, "FocalPlaneXResolution",
	 N_("Focal Plane X-Resolution"),
	 N_("Indicates the number of pixels in the image width (X) direction "
	    "per <FocalPlaneResolutionUnit> on the camera focal plane."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_FOCAL_PLANE_Y_RESOLUTION, "FocalPlaneYResolution",
	 N_("Focal Plane Y-Resolution"),
	 N_("Indicates the number of pixels in the image height (V) direction "
	    "per <FocalPlaneResolutionUnit> on the camera focal plane."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_FOCAL_PLANE_RESOLUTION_UNIT, "FocalPlaneResolutionUnit",
	 N_("Focal Plane Resolution Unit"),
	 N_("Indicates the unit for measuring <FocalPlaneXResolution> and "
	    "<FocalPlaneYResolution>. This value is the same as the "
	    "<ResolutionUnit>."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_SUBJECT_LOCATION, "SubjectLocation",
	 N_("Subject Location"),
	 N_("Indicates the location of the main subject in the scene. The "
	    "value of this tag represents the pixel at the center of the "
	    "main subject relative to the left edge, prior to rotation "
	    "processing as per the <Rotation> tag. The first value "
	    "indicates the X column number and the second indicates "
	    "the Y row number."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_EXPOSURE_INDEX, "ExposureIndex", N_("Exposure Index"),
	 N_("Indicates the exposure index selected on the camera or "
	    "input device at the time the image is captured."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_SENSING_METHOD, "SensingMethod", N_("Sensing Method"),
	 N_("Indicates the image sensor type on the camera or input "
	    "device."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_FILE_SOURCE, "FileSource", N_("File Source"),
	 N_("Indicates the image source. If a DSC recorded the image, "
	    "the tag value of this tag always be set to 3, indicating "
	    "that the image was recorded on a DSC."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_SCENE_TYPE, "SceneType", N_("Scene Type"),
	 N_("Indicates the type of scene. If a DSC recorded the image, "
	    "this tag value must always be set to 1, indicating that the "
	    "image was directly photographed."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_NEW_CFA_PATTERN, "CFAPattern",
	 N_("CFA Pattern"),
	 N_("Indicates the color filter array (CFA) geometric pattern of the "
	    "image sensor when a one-chip color area sensor is used. "
	    "It does not apply to all sensing methods."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_CUSTOM_RENDERED, "CustomRendered", N_("Custom Rendered"),
	 N_("This tag indicates the use of special processing on image "
	    "data, such as rendering geared to output. When special "
	    "processing is performed, the reader is expected to disable "
	    "or minimize any further processing."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_EXPOSURE_MODE, "ExposureMode", N_("Exposure Mode"),
	 N_("This tag indicates the exposure mode set when the image was "
	    "shot. In auto-bracketing mode, the camera shoots a series of "
	    "frames of the same scene at different exposure settings."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_WHITE_BALANCE, "WhiteBalance", N_("White Balance"),
	 N_("This tag indicates the white balance mode set when the image "
	    "was shot."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_DIGITAL_ZOOM_RATIO, "DigitalZoomRatio",
	 N_("Digital Zoom Ratio"),
	 N_("This tag indicates the digital zoom ratio when the image was "
	    "shot. If the numerator of the recorded value is 0, this "
	    "indicates that digital zoom was not used."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_FOCAL_LENGTH_IN_35MM_FILM, "FocalLengthIn35mmFilm",
	 N_("Focal Length in 35mm Film"),
	 N_("This tag indicates the equivalent focal length assuming a "
	    "35mm film camera, in mm. A value of 0 means the focal "
	    "length is unknown. Note that this tag differs from the "
	    "FocalLength tag."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_SCENE_CAPTURE_TYPE, "SceneCaptureType",
	 N_("Scene Capture Type"),
	 N_("This tag indicates the type of scene that was shot. It can "
	    "also be used to record the mode in which the image was "
	    "shot. Note that this differs from the scene type "
	    "<SceneType> tag."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_GAIN_CONTROL, "GainControl", N_("Gain Control"),
	 N_("This tag indicates the degree of overall image gain "
	    "adjustment."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_CONTRAST, "Contrast", N_("Contrast"),
	 N_("This tag indicates the direction of contrast processing "
	    "applied by the camera when the image was shot."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_SATURATION, "Saturation", N_("Saturation"),
	 N_("This tag indicates the direction of saturation processing "
	    "applied by the camera when the image was shot."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_SHARPNESS, "Sharpness", N_("Sharpness"),
	 N_("This tag indicates the direction of sharpness processing "
	    "applied by the camera when the image was shot."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_DEVICE_SETTING_DESCRIPTION, "DeviceSettingDescription",
	 N_("Device Setting Description"),
	 N_("This tag indicates information on the picture-taking "
	    "conditions of a particular camera model. The tag is used "
	    "only to indicate the picture-taking conditions in the "
	    "reader."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_SUBJECT_DISTANCE_RANGE, "SubjectDistanceRange",
	 N_("Subject Distance Range"),
	 N_("This tag indicates the distance to the subject."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	{EXIF_TAG_IMAGE_UNIQUE_ID, "ImageUniqueID", N_("Image Unique ID"),
	 N_("This tag indicates an identifier assigned uniquely to "
	    "each image. It is recorded as an ASCII string equivalent "
	    "to hexadecimal notation and 128-bit fixed length."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	/* EXIF 2.3 */
	{EXIF_TAG_CAMERA_OWNER_NAME, "CameraOwnerName", N_("Camera Owner Name"),
	 N_("This tag indicates the name of the camera owner, "
            "photographer or image creator."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	/* EXIF 2.3 */
	{EXIF_TAG_BODY_SERIAL_NUMBER, "BodySerialNumber", N_("Body Serial Number"),
	 N_("This tag indicates the serial number of the body of the camera"),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	/* EXIF 2.3 */
	{EXIF_TAG_LENS_SPECIFICATION, "LensSpecification", N_("Lens Specification"),
	 N_("This tag indicates minimum focal length, "
            "maximum focal length, minimum F number in the "
            "minimum focal length, and minimum F number in "
            "the maximum focal length."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	/* EXIF 2.3 */
	{EXIF_TAG_LENS_MAKE, "LensMake", N_("Lens Make"),
	 N_("This tag indicates the lens manufacturer."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	/* EXIF 2.3 */
	{EXIF_TAG_LENS_MODEL, "LensModel", N_("Lens Model"),
	 N_("This tag indicates the lens' model name and model number."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	/* EXIF 2.3 */
	{EXIF_TAG_LENS_SERIAL_NUMBER, "LensSerialNumber", N_("Lens Serial Number"),
	 N_("This tag indicates the serial number of the interchangeable lens."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	/* EXIF 2.32 */
	{EXIF_TAG_COMPOSITE_IMAGE, "CompositeImage", N_("Composite Image"),
	 N_("This tag indicates whether this image was composed from multiple images"),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	/* EXIF 2.32 */
	{EXIF_TAG_SOURCE_IMAGE_NUMBER_OF_COMPOSITE_IMAGE, "SourceImageNumberOfCompositeImage", N_("Source Image Number Of Composite Image"),
	 N_("This tag indicates how many images are included and used in the composition of this image"),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	/* EXIF 2.32 */
	{EXIF_TAG_SOURCE_EXPOSURE_TIMES_OF_COMPOSITE_IMAGE, "SourceExposureTimesOfCompositeImage", N_("Source Exposure Times of Composite Image"),
	 N_("This tag indicates the exposure times of the source images of this image"),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	/* EXIF 2.3 */
	{EXIF_TAG_GAMMA, "Gamma", N_("Gamma"),
	 N_("Indicates the value of coefficient gamma."),
	 { ESL_NNNN, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
	/* Not in EXIF 2.2 */
	{EXIF_TAG_PRINT_IMAGE_MATCHING, "PrintImageMatching", N_("PRINT Image Matching"),
	 N_("Related to Epson's PRINT Image Matching technology"),
	 ESL_UNKNOWN},
	/* Not in EXIF 2.2 (from the Microsoft HD Photo specification) */
	{EXIF_TAG_PADDING, "Padding", N_("Padding"),
	 N_("This tag reserves space that can be reclaimed later when "
            "additional metadata are added. New metadata can be written "
            "in place by replacing this tag with a smaller data element "
            "and using the reclaimed space to store the new or expanded "
            "metadata tags."),
	 { ESL_OOOO, ESL_NNNN, ESL_OOOO, ESL_NNNN, ESL_NNNN } },
#endif
	{0, NULL, NULL, NULL, ESL_UNKNOWN}
};

/* For now, do not use these functions. */

/*!
 * Return the number of entries in the EXIF tag table, including the
 * terminating NULL entry.
 */
unsigned int
exif_tag_table_count (void)
{
	return sizeof (ExifTagTable) / sizeof (ExifTagTable[0]);
}


ExifTag
exif_tag_table_get_tag (unsigned int n)
{
	return (n < exif_tag_table_count ()) ? ExifTagTable[n].tag : 0;
}

const char *
exif_tag_table_get_name (unsigned int n)
{
	return (n < exif_tag_table_count ()) ? ExifTagTable[n].name : NULL;
}

/*!
 * Compares the tag with that in entry.
 * \param[in] tag pointer to integer tag value
 * \param[in] entry pointer to a struct TagEntry
 * \return 0 if tags are equal, <0 if tag < entry, >0 if tag > entry
 */
static int
match_tag(const void *tag, const void *entry)
{
	return *(int*)tag - ((struct TagEntry *)entry)->tag;
}


/*!
 * Finds the first entry in the EXIF tag table with the given tag number
 * using a binary search.
 * \param[in] tag to find
 * \return index into table, or -1 if not found
 */
static int
exif_tag_table_first(ExifTag tag)
{
	int i;
	struct TagEntry *entry = bsearch(&tag, ExifTagTable,
		exif_tag_table_count()-1, sizeof(struct TagEntry), match_tag);
	if (!entry)
		return -1;	/* Not found */

	/* Calculate index of found entry */
	i = entry - ExifTagTable;

	/* There may be other entries with the same tag number, so search
	 * backwards to find the first
	 */
	while ((i > 0) && (ExifTagTable[i-1].tag == tag)) {
		--i;
	}
	return i;
}

#define RECORDED \
((ExifTagTable[i].esl[ifd][EXIF_DATA_TYPE_UNCOMPRESSED_CHUNKY] != EXIF_SUPPORT_LEVEL_NOT_RECORDED) || \
 (ExifTagTable[i].esl[ifd][EXIF_DATA_TYPE_UNCOMPRESSED_PLANAR] != EXIF_SUPPORT_LEVEL_NOT_RECORDED) || \
 (ExifTagTable[i].esl[ifd][EXIF_DATA_TYPE_UNCOMPRESSED_YCC] != EXIF_SUPPORT_LEVEL_NOT_RECORDED) || \
 (ExifTagTable[i].esl[ifd][EXIF_DATA_TYPE_COMPRESSED] != EXIF_SUPPORT_LEVEL_NOT_RECORDED))

const char *
exif_tag_get_name_in_ifd (ExifTag tag, ExifIfd ifd)
{
	unsigned int i;
	int first;

	if (ifd >= EXIF_IFD_COUNT)
		return NULL;
	first = exif_tag_table_first(tag);
	if (first < 0)
		return NULL;

	for (i = first; ExifTagTable[i].name; i++) {
		if (ExifTagTable[i].tag == tag) {
		   if (RECORDED)
			   break;
		} else
			return NULL; /* Recorded tag not found in the table */
	}
	return ExifTagTable[i].name;
}

const char *
exif_tag_get_title_in_ifd (ExifTag tag, ExifIfd ifd)
{
	unsigned int i;
	int first;

	if (ifd >= EXIF_IFD_COUNT)
		return NULL;
	first = exif_tag_table_first(tag);
	if (first < 0)
		return NULL;

	for (i = first; ExifTagTable[i].name; i++) {
		if (ExifTagTable[i].tag == tag) {
		   if (RECORDED)
			   break;
		} else
			return NULL; /* Recorded tag not found in the table */
	}
	(void) bindtextdomain (GETTEXT_PACKAGE, LOCALEDIR);
	return _(ExifTagTable[i].title);
}

const char *
exif_tag_get_description_in_ifd (ExifTag tag, ExifIfd ifd)
{
	unsigned int i;
	int first;

	if (ifd >= EXIF_IFD_COUNT)
		return NULL;
	first = exif_tag_table_first(tag);
	if (first < 0)
		return NULL;

	for (i = first; ExifTagTable[i].name; i++) {
		if (ExifTagTable[i].tag == tag) {
			if (RECORDED)
				break;
		} else
			return NULL; /* Recorded tag not found in the table */
	}

	/* GNU gettext acts strangely when given an empty string */
	if (!ExifTagTable[i].description || !*ExifTagTable[i].description)
		return "";

	/* libexif should use the default system locale.
	 * If an application specifically requires UTF-8, then we
	 * must give the application a way to tell libexif that.
	 * 
	 * bind_textdomain_codeset (GETTEXT_PACKAGE, "UTF-8");
	 */
	(void) bindtextdomain (GETTEXT_PACKAGE, LOCALEDIR);
	return _(ExifTagTable[i].description);
}


/**********************************************************************
 * convenience functions
 **********************************************************************/

/* generic part: iterate through IFD list and return first result */
typedef const char * (*get_stuff_func) (ExifTag tag, ExifIfd ifd);

static const char *
exif_tag_get_stuff (ExifTag tag, get_stuff_func func)
{
	/* Search IFDs in this order, in decreasing order of number of valid tags */
	static const ExifIfd ifds[EXIF_IFD_COUNT] = {
		EXIF_IFD_EXIF,
		EXIF_IFD_0,
		EXIF_IFD_1,
		EXIF_IFD_INTEROPERABILITY,
		EXIF_IFD_GPS
	};
	int i;
	for (i=0; i<EXIF_IFD_COUNT; i++) {
		const char *result = func(tag, ifds[i]);
		if (result != NULL) {
			return result;
		}
	}
	return (const char *) NULL;
}

/* explicit functions */
const char *
exif_tag_get_name (ExifTag tag)
{
	return exif_tag_get_stuff(tag, exif_tag_get_name_in_ifd);
}

const char *
exif_tag_get_title (ExifTag tag)
{
	return exif_tag_get_stuff(tag, exif_tag_get_title_in_ifd);
}

const char *
exif_tag_get_description (ExifTag tag)
{
	return exif_tag_get_stuff(tag, exif_tag_get_description_in_ifd);
}



ExifTag 
exif_tag_from_name (const char *name)
{
	unsigned int i;
	unsigned int result=0;

	if (!name) return 0;

	for (i = 0; ExifTagTable[i].name; i++)
		if (!strcmp (ExifTagTable[i].name, name))  {
		  	result = ExifTagTable[i].tag;
		  	break;
		}
	return result;
}

/*! Return the support level of a tag in the given IFD with the given data
 * type. If the tag is not specified in the EXIF standard, this function
 * returns EXIF_SUPPORT_LEVEL_NOT_RECORDED.
 *
 * \param[in] tag EXIF tag
 * \param[in] ifd a valid IFD (not EXIF_IFD_COUNT)
 * \param[in] t a valid data type (not EXIF_DATA_TYPE_UNKNOWN)
 * \return the level of support for this tag
 */
static inline ExifSupportLevel
get_support_level_in_ifd (ExifTag tag, ExifIfd ifd, ExifDataType t)
{
	unsigned int i;
	int first = exif_tag_table_first(tag);
	if (first < 0)
		return EXIF_SUPPORT_LEVEL_NOT_RECORDED;

	for (i = first; ExifTagTable[i].name; i++) {
		if (ExifTagTable[i].tag == tag) {
			const ExifSupportLevel supp = ExifTagTable[i].esl[ifd][t];
			if (supp != EXIF_SUPPORT_LEVEL_NOT_RECORDED)
				return supp;
			/* Try looking for another entry */
		} else {
			break; /* We've reached the end of the matching tags */
		}
	}
	return EXIF_SUPPORT_LEVEL_NOT_RECORDED;
}

/*! Return the support level of a tag in the given IFD, regardless of the
 * data type. If the support level varies depending on the data type, this
 * function returns EXIF_SUPPORT_LEVEL_UNKNOWN. If the tag is not specified
 * in the EXIF standard, this function returns EXIF_SUPPORT_LEVEL_UNKNOWN.
 *
 * \param[in] tag EXIF tag
 * \param[in] ifd a valid IFD (not EXIF_IFD_COUNT)
 * \return the level of support for this tag
 */
static inline ExifSupportLevel
get_support_level_any_type (ExifTag tag, ExifIfd ifd)
{
	unsigned int i;
	int first = exif_tag_table_first(tag);
	if (first < 0)
		return EXIF_SUPPORT_LEVEL_UNKNOWN;

	for (i = first; ExifTagTable[i].name; i++) {
		if (ExifTagTable[i].tag == tag) {
			/*
			 * Check whether the support level is the same for all possible
			 * data types and isn't marked not recorded.
			 */
			const ExifSupportLevel supp = ExifTagTable[i].esl[ifd][0];
			/* If level is not recorded, keep searching for another */
			if (supp != EXIF_SUPPORT_LEVEL_NOT_RECORDED) {
				unsigned int dt;
				for (dt = 0; dt < EXIF_DATA_TYPE_COUNT; ++dt) {
					if (ExifTagTable[i].esl[ifd][dt] != supp)
						break;
				}
				if (dt == EXIF_DATA_TYPE_COUNT)
					/* Support level is always the same, so return it */
					return supp;
			}
			/* Keep searching the table for another tag for our IFD */
		} else {
			break; /* We've reached the end of the matching tags */
		}
	}
	return EXIF_SUPPORT_LEVEL_UNKNOWN;
}

ExifSupportLevel
exif_tag_get_support_level_in_ifd (ExifTag tag, ExifIfd ifd, ExifDataType t)
{
	if (ifd >= EXIF_IFD_COUNT)
		return EXIF_SUPPORT_LEVEL_UNKNOWN;

	if (t >= EXIF_DATA_TYPE_COUNT)
		return get_support_level_any_type (tag, ifd);

	return get_support_level_in_ifd (tag, ifd, t);
}
