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Image::ExifTool::MIE(3User Contributed Perl DocumentatiImage::ExifTool::MIE(3)

NAME
       Image::ExifTool::MIE - Read/write MIE meta information

SYNOPSIS
       This module is used by Image::ExifTool

DESCRIPTION
       This module contains routines required by Image::ExifTool to read and
       write information in MIE	files.

WHAT IS	MIE?
       MIE stands for "Meta Information	Encapsulation".	 The MIE format	is an
       extensible, dedicated meta information format which supports storage of
       binary as well as textual meta information.  MIE	can be used to
       encapsulate meta	information from many sources and bundle it together
       with any	type of	file.

   Features
       Below is	very subjective	score card comparing the features of a number
       of common file and meta information formats, and	comparing them to MIE.
       The following features are rated	for each format	with a score of	0 to
       10:

	 1) Extensible (can incorporate	user-defined information).
	 2) Meaningful tag ID's	(hint to meaning of unknown information).
	 3) Sequential read/write ability (streamable).
	 4) Hierarchical information structure.
	 5) Easy to implement reader/writer/editor.
	 6) Order of information well defined.
	 7) Large data lengths supported: >64kB	(+5) and >4GB (+5).
	 8) Localized text strings.
	 9) Multiple documents in a single file.
	10) Compact format doesn't squander disk space or bandwidth.
	11) Compressed meta information	supported.
	12) Relocatable	data elements (ie. no fixed offsets).
	13) Binary meta	information (+7) with variable byte order (+3).
	14) Mandatory tags not required	(an unnecessary	complication).
	15) Append information to end of file without editing.

				 Feature number			  Total
	    Format  1  2  3  4	5  6  7	 8  9 10 11 12 13 14 15	  Score
	    ------ ---------------------------------------------  -----
	    MIE	   10 10 10 10 10 10 10	10 10 10 10 10 10 10 10	   150
	    PDF	   10 10  0 10	0  0 10	 0 10 10 10  0	7 10 10	    97
	    PNG	   10 10 10  0	8  0  5	10  0 10 10 10	0 10  0	    93
	    XMP	   10 10 10 10	2  0 10	10 10  0  0 10	0 10  0	    92
	    AIFF    0  5 10 10 10  0  5	 0  0 10  0 10	7 10  0	    77
	    RIFF    0  5 10 10 10  0  5	 0  0 10  0 10	7 10  0	    77
	    JPEG   10  0 10  0 10  0  0	 0  0 10  0 10	7 10  0	    67
	    EPS	   10 10 10  0	0  0 10	 0 10  0  0  5	0 10  0	    65
	    CIFF    0  0  0 10 10  0  5	 0  0 10  0 10 10 10  0	    65
	    TIFF    0  0  0 10	5 10  5	 0 10 10  0  0 10  0  0	    60
	    EXIF    0  0  0 10	5 10  0	 0  0 10  0  0 10  0  0	    45
	    IPTC    0  0 10  0	8  0  0	 0  0 10  0 10	7  0  0	    45

       By design, MIE ranks highest by a significant margin.  Other formats
       with reasonable scores are PDF, PNG and XMP, but	each has significant
       weak points.  What may be surprising is that TIFF, EXIF and IPTC	rank
       so low.

       As well as scoring high in all these features, the MIE format has the
       unique ability to encapsulate any other type of file, and provides a
       non-invasive method of adding meta information to a file.  The meta
       information is logically	separated from the original file data, which
       is extremely important because meta information is routinely lost when
       files are edited.

       Also, the MIE format supports multiple files by simple concatenation,
       enabling	all kinds of wonderful features	such as	linear databases, edit
       histories or non-intrusive file updates.	 This ability can also be
       leveraged to allow MIE-format trailers to be added to some other	file
       types.

MIE 1.1	FORMAT SPECIFICATION (2007-01-21)
   File	Structure
       A MIE file consists of a	series of MIE elements.	 A MIE element may
       contain either data or a	group of MIE elements, providing a
       hierarchical format for storing data.  Each MIE element is identified
       by a human-readable tag name, and may store data	from zero to 2^64-1
       bytes in	length.

   File	Signature
       The first element in the	MIE file must be an uncompressed MIE group
       element with a tag name of "0MIE".  This	restriction allows the first 8
       bytes of	a MIE file to be used to identify a MIE	format file.  The
       following table lists the two possible initial byte sequences for a
       MIE-format file (the first for big-endian, and the second for little-
       endian byte ordering):

	   Byte	Number:	     0	  1    2    3	 4    5	   6	7

	   C Characters:     ~ \x10 \x04    ?	 0    M	   I	E
	       or	     ~ \x18 \x04    ?	 0    M	   I	E

	   Hexadecimal:	    7e	 10   04    ?	30   4d	  49   45
	       or	    7e	 18   04    ?	30   4d	  49   45

	   Decimal:	   126	 16    4    ?	48   77	  73   69
	       or	   126	 24    4    ?	48   77	  73   69

       Note that byte 1	may have one of	the two	possible values	(0x10 or
       0x18), and byte 3 may have any value (0x00 to 0xff).

   Element Structure
	   1 byte  SyncByte = 0x7e (decimal 126, character '~')
	   1 byte  FormatCode (see below)
	   1 byte  TagLength (T)
	   1 byte  DataLength (gives D if DataLength < 253)
	   T bytes TagName (T given by TagLength)
	   2 bytes DataLength2 [exists only if DataLength == 255 (0xff)]
	   4 bytes DataLength4 [exists only if DataLength == 254 (0xfe)]
	   8 bytes DataLength8 [exists only if DataLength == 253 (0xfd)]
	   D bytes DataBlock (D	given by DataLength)

       The minimum element length is 4 bytes (for a group terminator).	The
       maximum DataBlock size is 2^64-1	bytes.	TagLength and DataLength are
       unsigned	integers, and the byte ordering	for multi-byte DataLength
       fields is specified by the containing MIE group element.	 The SyncByte
       is byte aligned,	so no padding is added to align	on an N-byte boundary.

       FormatCode

       The format code is a bitmask that defines the format of the data:

	   7654	3210
	   ++++	----  FormatType
	   ----	+---  TypeModifier
	   ----	-+--  Compressed
	   ----	--++  FormatSize

       FormatType (bitmask 0xf0):
	       0x00 - other (or	unknown) data
	       0x10 - MIE group
	       0x20 - text string
	       0x30 - list of null-separated text strings
	       0x40 - integer
	       0x50 - rational
	       0x60 - fixed point
	       0x70 - floating point
	       0x80 - free space

       TypeModifier (bitmask 0x08):
	   Modifies the	meaning	of certain FormatTypes (0x00-0x60):

	       0x08 - other data sensitive to MIE group	byte order
	       0x18 - MIE group	with little-endian byte	ordering
	       0x28 - UTF encoded text string
	       0x38 - UTF encoded text string list
	       0x48 - signed integer
	       0x58 - signed rational (denominator is always unsigned)
	       0x68 - signed fixed-point

       Compressed (bitmask 0x04):
	   If this bit is set, the data	block is compressed using Zlib
	   deflate.  An	entire MIE group may be	compressed, with the exception
	   of file-level groups.

       FormatSize (bitmask 0x03):
	   Gives the byte size of each data element:

	       0x00 - 8	bits  (1 byte)
	       0x01 - 16 bits (2 bytes)
	       0x02 - 32 bits (4 bytes)
	       0x03 - 64 bits (8 bytes)

	   The number of bytes in a single value for this format is given by
	   2**FormatSize (or 1 << FormatSize).	The number of values is	the
	   data	length divided by this number of bytes.	 It is an error	if the
	   data	length is not an even multiple of the format size in bytes.

       The following is	a list of all currently	defined	MIE FormatCode values
       for uncompressed	data (add 0x04 to each value for compressed data):

	   0x00	- other	data (insensitive to MIE group byte order) (1)
	   0x01	- other	16-bit data (may be byte swapped)
	   0x02	- other	32-bit data (may be byte swapped)
	   0x03	- other	64-bit data (may be byte swapped)
	   0x08	- other	data (sensitive	to MIE group byte order) (1)
	   0x10	- MIE group with big-endian values (1)
	   0x18	- MIE group with little-endian values (1)
	   0x20	- ASCII	(ISO 8859-1) string (2,3)
	   0x28	- UTF-8	string (2,3,4)
	   0x29	- UTF-16 string	(2,3,4)
	   0x2a	- UTF-32 string	(2,3,4)
	   0x30	- ASCII	(ISO 8859-1) string list (3,5)
	   0x38	- UTF-8	string list (3,4,5)
	   0x39	- UTF-16 string	list (3,4,5)
	   0x3a	- UTF-32 string	list (3,4,5)
	   0x40	- unsigned 8-bit integer
	   0x41	- unsigned 16-bit integer
	   0x42	- unsigned 32-bit integer
	   0x43	- unsigned 64-bit integer (6)
	   0x48	- signed 8-bit integer
	   0x49	- signed 16-bit	integer
	   0x4a	- signed 32-bit	integer
	   0x4b	- signed 64-bit	integer	(6)
	   0x52	- unsigned 32-bit rational (16-bit numerator then denominator) (7)
	   0x53	- unsigned 64-bit rational (32-bit numerator then denominator) (7)
	   0x5a	- signed 32-bit	rational (denominator is unsigned) (7)
	   0x5b	- signed 64-bit	rational (denominator is unsigned) (7)
	   0x61	- unsigned 16-bit fixed-point (high 8 bits is integer part) (8)
	   0x62	- unsigned 32-bit fixed-point (high 16 bits is integer part) (8)
	   0x69	- signed 16-bit	fixed-point (high 8 bits is signed integer) (8)
	   0x6a	- signed 32-bit	fixed-point (high 16 bits is signed integer) (8)
	   0x72	- 32-bit IEEE float (not recommended for portability reasons)
	   0x73	- 64-bit IEEE double (not recommended for portability reasons) (6)
	   0x80	- free space (value data does not contain useful information)

       Notes:

       1.  The byte ordering specified by the MIE group	TypeModifier applies
	   to the MIE group element as well as all elements within the group.
	   Data	for all	FormatCodes except 0x08	(other data, sensitive to byte
	   order) may be transferred between MIE groups	with different byte
	   order by byte swapping the uncompressed data	according to the
	   specified data format.  The following list illustrates the byte-
	   swapping pattern, based on FormatSize, for all format types except
	   rational (FormatType	0x50).

		 FormatSize		 Change	in Byte	Sequence
	       --------------	   -----------------------------------
	       0x00 (8 bits)	   0 1 2 3 4 5 6 7 --> 0 1 2 3 4 5 6 7 (no change)
	       0x01 (16	bits)	   0 1 2 3 4 5 6 7 --> 1 0 3 2 5 4 7 6
	       0x02 (32	bits)	   0 1 2 3 4 5 6 7 --> 3 2 1 0 7 6 5 4
	       0x03 (64	bits)	   0 1 2 3 4 5 6 7 --> 7 6 5 4 3 2 1 0

	   Rational values consist of two integers, so they are	swapped	as the
	   next	lower FormatSize.  For example,	a 32-bit rational (FormatSize
	   0x02, and FormatCode	0x52 or	0x5a) is swapped as two	16-bit values
	   (ie.	as if it had FormatSize	0x01).

       2.  The TagName of a string element may have an 6-character suffix to
	   indicate a specific locale. (eg. "Title-en_US", or
	   "Keywords-de_DE").

       3.  Text	strings	are not	normally null terminated, however they may be
	   padded with one or more null	characters to the end of the data
	   block to allow strings to be	edited within fixed-length data
	   blocks.  Newlines in	the text are indicated by a single LF (0x0a)
	   character.

       4.  UTF strings must not	begin with a byte order	mark (BOM) since the
	   byte	order and byte size are	specified by the MIE format.  If a BOM
	   is found, it	should be treated as a zero-width non-breaking space.

       5.  A list of text strings separated by null characters.	 These lists
	   must	not be null padded or null terminated, since this would	be
	   interpreted as additional zero-length strings.  For ASCII and UTF-8
	   strings, the	null character is a single zero	(0x00) byte.  For
	   UTF-16 or UTF-32 strings, the null character	is 2 or	4 zero bytes
	   respectively.

       6.  64-bit integers and doubles are subject to the specified byte
	   ordering for	both 32-bit words and bytes within these words.	 For
	   instance, the high order byte is always the first byte if big-
	   endian, and the eighth byte if little-endian.  This means that some
	   swapping is always necessary	for these values on systems where the
	   byte	order differs from the word order (eg. some ARM	systems),
	   regardless of the endian-ness of the	stored values.

       7.  Rational values are treated as two separate integers.  The
	   numerator always comes first	regardless of the byte ordering.  In a
	   signed rational value, only the numerator is	signed.	 The
	   denominator of all rational values is unsigned (eg. a signed	64-bit
	   rational of 0x80000000/0x80000000 evaluates to -1, not +1).

       8.  32-bit fixed	point values are converted to floating point by
	   treating them as an integer and dividing by an appropriate value.
	   eg)

	       16-bit fixed value = 16-bit integer value / 256.0
	       32-bit fixed value = 32-bit integer value / 65536.0

       TagLength

       Gives the length	of the TagName string.	Any value between 0 and	255 is
       valid, but the TagLength	of 0 is	valid only for the MIE group
       terminator.

       DataLength

       DataLength is an	unsigned byte that gives the number of bytes in	the
       data block.  A value between 0 and 252 gives the	data length directly,
       and numbers from	253 to 255 are reserved	for extended DataLength	codes.
       Codes of	255, 254 and 253 indicate that the element contains an
       additional 2, 4 or 8 byte unsigned integer representing the data
       length.

	   0-252      -	length of data block
	   255 (0xff) -	use DataLength2
	   254 (0xfe) -	use DataLength4
	   253 (0xfd) -	use DataLength8

       A DataLength of zero is valid for any element except a compressed MIE
       group.  A zero DataLength for an	uncompressed MIE group indicates that
       the group length	is unknown.  For other elements, a zero	length
       indicates there is no associated	data.  A terminator element must have
       a DataLength of 0, 6 or 10, and may not use an extended DataLength.

       TagName

       The TagName string is 0 to 255 bytes long, and is composed of the ASCII
       characters A-Z, a-z, 0-9	and underline ('_').  Also, a dash ('-') is
       used to separate	the language/country code in the TagName of a
       localized text string, and a units string (possibly containing other
       ASCII characters) may be	appear in brackets at the end of the TagName.
       The TagName string is NOT null terminated.  A MIE element with a	tag
       string of zero length is	reserved for the group terminator.

       MIE elements are	sorted alphabetically by TagName within	each group.
       Multiple	elements with the same TagName are allowed, even within	the
       same group.

       TagNames	should be meaningful.  Case is significant.  Words should be
       lowercase with an uppercase first character, and	acronyms should	be all
       upper case.  The	underline ("_")	is provided to allow separation	of two
       acronyms	or two numbers,	but it shouldn't be used unless	necessary.  No
       separation is necessary between an acronym and a	word (eg.
       "ISOSetting").

       All TagNames should start with an uppercase letter.  An exception to
       this rule allows	tags to	begin with a digit (0-9) if they must come
       before other tags in the	sort order, or a lowercase letter (a-z)	if
       they must come after.  For instance, the	'0Type'	element	begins with a
       digit so	it comes before, and the 'data'	element	begins with a
       lowercase letter	so that	it comes after meta information	tags in	the
       main "0MIE" group.

       Tag names for localized text strings have an 6-character	suffix with
       the following format:  The first	character is a dash ('-'), followed by
       a 2-character lower case	ISO 639-1 language code, then an underline
       ('_'), and ending with a	2-character upper case ISO 3166-1 alpha	2
       country code.  (eg.  "-en_US", "-en_GB",	"-de_DE" or "-fr_FR".  Note
       that "GB", and not "UK" is the code for Great Britain, although "UK"
       should be recognized for	compatibility reasons.)	 The suffix is
       included	when sorting the tags alphabetically, so the default locale
       (with no	tag-name suffix) always	comes first.  If the country is
       unknown or not applicable, a country code of "XX" should	be used.

       Tags with numerical values may allow units of measurement to be
       specified.  The units string is stored in brackets at the end of	the
       tag name, and is	composed of zero or more ASCII characters in the range
       0x21 to 0x7d, excluding the bracket characters 0x28 and 0x29.  (eg.
       "Resolution(/cm)" or "SpecificHeat(J/kg.K)".)  See
       Image::ExifTool::MIEUnits for details. Unit strings are not localized,
       and may not be used in combination with localized text strings.

       Sets of tags which would	require	a common prefix	should be added	in a
       separate	MIE group instead of adding the	prefix to all tag names.  For
       example,	instead	of these TagName's:

	   ExternalFlashType
	   ExternalFlashSerialNumber
	   ExternalFlashFired

       one would instead designate a separate "ExternalFlash" MIE group	to
       contain the following elements:

	   Type
	   SerialNumber
	   Fired

       DataLength2/4/8

       These extended DataLength fields	exist only if DataLength is 255, 254
       or 253, and are respectively 2, 4 or 8 byte unsigned integers giving
       the data	block length.  One of these values must	be used	if the data
       block is	larger than 252	bytes, but they	may be used if desired for
       smaller blocks too (although this may add a few unnecessary bytes to
       the MIE element).

       DataBlock

       The data	value for the MIE element.  The	format of the data is given by
       the FormatCode.	For MIE	group elements,	the data includes all
       contained elements and the group	terminator.

   MIE groups
       All MIE data elements must be contained within a	group.	A group	begins
       with a MIE group	element, and ends with a group terminator.  Groups may
       be nested in a hierarchy	to arbitrary depth.

       A MIE group element is identified by a format code of 0x10 (big endian
       byte ordering) or 0x18 (little endian).	The group terminator is
       distinguished by	a zero TagLength (it is	the only element allowed to
       have a zero TagLength), and has a FormatCode of 0x00.

       The MIE group element is	permitted to have a zero DataLength only if
       the data	is uncompressed.  This special value indicates that the	group
       length is unknown (otherwise the	minimum	value for DataLength is	4,
       corresponding the the minimum group size	which includes a terminator of
       at least	4 bytes). If DataLength	is zero, all elements in the group
       must be parsed until the	group terminator is found.  If non-zero,
       DataLength includes the length of all elements contained	within the
       group, including	the group terminator.  Use of a	non-zero DataLength is
       encouraged because it allows readers quickly skip over entire MIE
       groups.	For compressed groups DataLength must be non-zero, and is the
       length of the compressed	group data (which includes the compressed
       group terminator).

       Group Terminator

       The group terminator has	a FormatCode and TagLength of zero.  The
       terminator DataLength must be 0,	6 or 10	bytes, and extended DataLength
       codes may not be	used.  With a zero DataLength, the byte	sequence for a
       terminator is "7e 00 00 00" (hex).  With	a DataLength of	6 or 10	bytes,
       the terminator data block contains information about the	length and
       byte ordering of	the preceding group.  This additional information is
       recommended for file-level groups, and is used in multi-document	MIE
       files and MIE trailers to allow the file	to be scanned backwards	from
       the end.	 (This may also	allow some documents to	be recovered if	part
       of the file is corrupted.)  The structure of this optional terminator
       data block is as	follows:

	   4 or	8 bytes	 GroupLength (unsigned integer)
	   1 byte	 ByteOrder (0x10 or 0x18, same as MIE group)
	   1 byte	 GroupLengthSize (0x04 or 0x08)

       The ByteOrder and GroupLengthSize values	give the byte ordering and
       size of the GroupLength integer.	 The GroupLength value is the total
       length of the entire MIE	group ending with this terminator, including
       the opening MIE group element and the terminator	itself.

       File-level MIE groups

       File-level MIE groups may NOT be	compressed.

       All elements in a MIE file are contained	within a special group with a
       TagName of "0MIE".  The purpose of the "OMIE" group is to provide a
       unique signature	at the start of	the file, and to encapsulate
       information allowing files to be	easily combined.  The "0MIE" group
       must be terminated like any other group,	but it is recommended that the
       terminator of a file-level group	include	the optional data block
       (defined	above) to provide information about the	group length and byte
       order.

       It is valid to have more	than one "0MIE"	group at the file level,
       allowing	multiple documents in a	single MIE file.  Furthermore, the MIE
       structure enables multi-document	files to be generated by simply
       concatenating two or more MIE files.

   Scanning Backwards through a	MIE File
       The steps below give an algorithm to quickly locate the last document
       in a MIE	file:

       1.  Read	the last 10 bytes of the file.	(Note that a valid MIE file
	   may be as short as 12 bytes long, but a file	this length contains
	   only	an an empty MIE	group.)

       2.  If the last byte of the file	is zero, then it is not	possible to
	   scan	backward through the file, so the file must be scanned from
	   the beginning.  Otherwise, proceed to the next step.

       3.  If the last byte is 4 or 8, the terminator contains information
	   about the byte ordering and length of the group.  Otherwise,	stop
	   here	because	this isn't a valid MIE file.

       4.  The next-to-last byte must be either	0x10 indicating	big-endian
	   byte	ordering or 0x18 for little-endian ordering, otherwise this
	   isn't a valid MIE file.

       5.  The value of	the preceding 4	or 8 bytes gives the length of the
	   complete file-level MIE group (GroupLength).	 This length includes
	   both	the leading MIE	group element and the terminator element
	   itself.  The	value is an unsigned integer with a byte length	given
	   in step 3), and a byte order	from step 4).  From the	current	file
	   position (at	the end	of the data read in step 1), seek backward by
	   this	number of bytes	to find	the start of the MIE group element for
	   this	document.

       This algorithm may be repeated again beginning at this point in the
       file to locate the next-to-last document, etc.

       The table below lists all 5 valid patterns for the last 14 bytes	of a
       file-level MIE group, with all numbers in hex.  The comments indicate
       the length and byte ordering of GroupLength (xx)	if available:

	 ?? ?? ?? ?? ??	?? ?? ?? ?? ?? 7e 00 00	00  - (no GroupLength)
	 ?? ?? ?? ?? 7e	00 00 06 xx xx xx xx 10	04  - 4	bytes, big endian
	 ?? ?? ?? ?? 7e	00 00 06 xx xx xx xx 18	04  - 4	bytes, little endian
	 7e 00 00 0a xx	xx xx xx xx xx xx xx 10	08  - 8	bytes, big endian
	 7e 00 00 0a xx	xx xx xx xx xx xx xx 18	08  - 8	bytes, little endian

   Trailer Signature
       The MIE format may be used for trailer information appended to other
       types of	files.	When this is done, a signature must appear at the end
       of the main MIE group to	uniquely identify the MIE format trailer.  To
       achieve this, a "zmie" trailer signature	is written as the last element
       in the main "0MIE" group.  This element has a FormatCode	of 0, a
       TagLength of 4, a DataLength of 0, and a	TagName	of "zmie".  With this
       signature, the hex byte sequence	"7e 00 04 00 7a	6d 69 65" appears
       immediately before the final group terminator, and the last 22 bytes of
       the trailer correspond to one of	the following 4	patterns (where	the
       trailer length is given by "xx",	as above):

	 ?? ?? ?? ?? 7e	00 04 00 7a 6d 69 65 7e	00 00 06 xx xx xx xx 10	04
	 ?? ?? ?? ?? 7e	00 04 00 7a 6d 69 65 7e	00 00 06 xx xx xx xx 18	04
	 7e 00 04 00 7a	6d 69 65 7e 00 00 0a xx	xx xx xx xx xx xx xx 10	08
	 7e 00 04 00 7a	6d 69 65 7e 00 00 0a xx	xx xx xx xx xx xx xx 18	08

       Note that the zero-DataLength terminator	may not	be used	here because
       the trailer length must be known	for seeking backwards from the end of
       the file.

       Multiple	trailers may be	appended to the	same file using	this
       technique.

   MIE Data Values
       MIE data	values for a given tag are usually not restricted to a
       specific	FormatCode.  Any value may be represented in any appropriate
       format, including numbers represented in	string (ASCII or UTF) form.

       It is preferred that closely related values with	the same format	are
       written to a single tag instead of using	multiple tags.	This improves
       localization of like values and decreases MIE element overhead.	For
       instance, instead of separate ImageWidth	and ImageHeight	tags, a	single
       ImageSize tag is	defined.

       Tags which may take on a	discrete set of	values should have meaningful
       values if possible.  This improves the extensibility of the format and
       allows a	more reasonable	interpretation of unrecognized values.

       Numerical Representation

       Integer and floating point numbers may be represented in	binary or
       string form.  In	string form, integers are a series of digits with an
       optional	leading	sign (eg. "[+|-]DDDDDD"), and multiple values are
       separated by a single space character (eg. "23 128 -32").  Floating
       point numbers are similar but may also contain a	decimal	point and/or a
       signed exponent with a leading 'e' character (eg.
       "[+|-]DD[.DDDDDD][e(+|-)EEE]").	The string "inf" is used to represent
       infinity.  One advantage	of numerical strings is	that they can have an
       arbitrarily high	precision because the possible number of significant
       digits is virtually unlimited.

       Note that numerical values may have associated units of measurement
       which are specified in the "TagName" string.

       Date/Time Format

       All MIE dates are strings in the	form "YYYY:mm:dd HH:MM:SS.ss+HH:MM".
       The fractional seconds (".ss") are optional, and	if included may
       contain any number of significant digits	(unlike	all other fields which
       are a fixed number of digits and	must be	padded with leading zeros if
       necessary).  The	timezone ("+HH:MM" or "-HH:MM")	is recommended but not
       required.  If not given,	the local system timezone is assumed.

   MIME	Type
       The basic MIME type for a MIE file is "application/x-mie", however the
       specific	MIME type depends on the type of subfile, and is obtained by
       adding "x-mie-" to the MIME type	of the subfile.	 For example, with a
       subfile of type "image/jpeg", the MIE file MIME type is
       "image/x-mie-jpeg".  But	note that the "x-" is not duplicated if	the
       subfile MIME type already starts	with "x-".  So a subfile with MIME
       type "image/x-raw" is contained within a	MIE file of type
       "image/x-mie-raw", not "image/x-mie-x-raw".  In the case	of multiple
       documents in a MIE file,	the MIME type is taken from the	first
       document.  Regardless of	the subfile type, all MIE-format files should
       have a filename extension of ".MIE".

   Levels of Support
       Basic MIE reader/writer applications may	choose not to provide support
       for some	advanced features of the MIE format.  Features which may not
       be supported by all software are:

       Compression
	   Software not	supporting compression must ignore compressed elements
	   and groups, but should be able to process the remaining
	   information.

       Large data lengths
	   Some	software may limit the maximum size of a MIE group or element.
	   Historically, a limit of 2GB	may be imposed by some systems.
	   However, 8-byte data	lengths	should be supported by all
	   applications	provided the value doesn't exceed the system limit.
	   (eg.	For systems with a 2GB limit, 8-byte data lengths should be
	   supported if	the upper 17 bits are all zero.)  If a data length
	   above the system limit is encountered, it may be necessary for the
	   application to stop processing if it	can not	seek to	the next
	   element in the file.

EXAMPLES
       This section gives examples for working with MIE	information using
       ExifTool.

   Encapsulating Information with Data in a MIE	File
       The following command encapsulates any file recognized by ExifTool
       inside a	MIE file, and initializes MIE tags from	information within the
       file:

	   exiftool -o new.mie -tagsfromfile FILE '-mie:all<all' \
	       '-subfilename<filename' '-subfiletype<filetype' \
	       '-subfilemimetype<mimetype' '-subfiledata<=FILE'

       where "FILE" is the name	of the file.

       For unrecognized	files, this command may	be used:

	   exiftool -o new.mie -subfilename=FILE -subfiletype=TYPE \
	       -subfilemimetype=MIME '-subfiledata<=FILE'

       where "TYPE" and	"MIME" represent the source file type and MIME type
       respectively.

   Adding a MIE	Trailer	to a File
       The MIE format may also be used to store	information in a trailer
       appended	to another type	of file.  Beware that trailers may not be
       compatible with all file	formats, but JPEG and TIFF are two formats
       where additional	trailer	information doesn't create any problems	for
       normal parsing of the file.  Also note that this	technique has the
       disadvantage that trailer information is	commonly lost if the file is
       subsequently edited by other software.

       Creating	a MIE trailer with ExifTool is a two-step process since
       ExifTool	can't currently	be used	to add a MIE trailer directly.	The
       example below illustrates the steps for adding a	MIE trailer with a
       small preview image ("small.jpg") to a destination JPEG image
       ("dst.jpg").

       Step 1) Create a	MIE file with a	TrailerSignature containing the
       desired information:

	   exiftool -o new.mie -trailersignature=1 -tagsfromfile small.jpg \
	       '-previewimagetype<filetype' '-previewimagesize<imagesize' \
	       '-previewimagename<filename' '-previewimage<=small.jpg'

       Step 2) Append the MIE information to another file.  In Unix, this can
       be done with the	'cat' command:

	   cat new.mie >> dst.jpg

       Once added, ExifTool may	be used	to edit	or delete a MIE	trailer	in a
       JPEG or TIFF image.

   Multiple MIE	Documents in a Single File
       The MIE specification allows multiple MIE documents (or trailers) to
       exist in	a single file.	A file like this may be	created	by simply
       concatenating MIE documents.  ExifTool may be used to access
       information in a	specific document by adding a copy number to the MIE
       group name.  For	example:

	   # write the Author tag in the second	MIE document
	   exiftool -mie2:author=phil test.mie

	   # delete the	first MIE document from	a file
	   exiftool -mie1:all= test.mie

   Units of Measurement
       Some MIE	tags allow values to be	specified in different units of
       measurement.  In	the MIE	file format these units	are combined with the
       tag name, but when using	ExifTool they are specified in brackets	after
       the value:

	   exiftool -mie:gpsaltitude='7500(ft)'	test.mie

       If no units are provided, the default units are written.

   Localized Text
       Localized text values are accessed by adding a language/country code to
       the tag name.  For example:

	   exiftool -comment-en_us='this is a comment' test.mie

REVISIONS
	 2010-04-05 - Fixed "Format Size" Note 7 to give the correct number of bits
		      in the example rational value
	 2007-01-21 - Specified	LF character (0x0a) for	text newline sequence
	 2007-01-19 - Specified	ISO 8859-1 character set for extended ASCII codes
	 2007-01-01 - Improved wording of Step 5 for scanning backwards	in MIE file
	 2006-12-30 - Added EXAMPLES section and note about UTF	BOM
	 2006-12-20 - MIE 1.1:	Changed	meaning	of TypeModifier	bit (0x08) for
		      unknown data (FormatType 0x00), and documented byte swapping
	 2006-12-14 - MIE 1.0:	Added Data Values and Numerical	Representations
		      sections,	and added ability to specify units in tag names
	 2006-11-09 - Added Levels of Support section
	 2006-11-03 - Added Trailer Signature
	 2005-11-18 - Original specification created

AUTHOR
       Copyright 2003-2017, Phil Harvey	(phil at owl.phy.queensu.ca)

       This library is free software; you can redistribute it and/or modify it
       under the same terms as Perl itself.  The MIE format itself is also
       copyright Phil Harvey, and is covered by	the same free-use license.

REFERENCES
       <http://owl.phy.queensu.ca/~phil/exiftool/MIE1.1-20070121.pdf>

SEE ALSO
       "MIE Tags" in Image::ExifTool::TagNames,	Image::ExifTool::MIEUnits,
       Image::ExifTool(3pm)

perl v5.32.0			  2017-01-03	       Image::ExifTool::MIE(3)

NAME | SYNOPSIS | DESCRIPTION | WHAT IS MIE? | MIE 1.1 FORMAT SPECIFICATION (2007-01-21) | EXAMPLES | REVISIONS | AUTHOR | REFERENCES | SEE ALSO

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