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<h2 class=top><a name='Composite'>MWG Composite Tags</a></h2>
<p>This table lists special Composite tags which are used to access other tags
based on the Metadata Working Group 1.01 recommendations. These tags are
only accessible when the MWG module is loaded (via <code>-use MWG</code> on the
command line, or <code>use Image::ExifTool::MWG</code> in the API). When reading, the
value of each MWG tag is <b>Derived From</b> the specified tags based on the MWG
guidelines. When writing, the value of the IPTCDigest tag is updated
automatically when the IPTC is changed if either the IPTCDigest tag didn't
exist beforehand or its value agreed with the original IPTC digest
(indicating that the XMP is synchronized with the IPTC). IPTC information
is written only if the original file contained IPTC. For more information
about the MWG recommendation, see <a href="http://www.metadataworkinggroup.org/">http://www.metadataworkinggroup.org/</a>.</p>
<p>A problem with the MWG specification is that although XMP:Creator and
IPTC:By-line are list-type tags, the corresponding EXIF tag, EXIF:Artist, is
not. So, short of changing the EXIF specification to allow EXIF:Artist to
store a list of strings, the only reasonable alternative is to NOT allow
MWG:Creator to be written as a list. (It is insufficient to say that
EXIF:Artist may store multiple strings separated with semicolons because
there is nothing in any of the MWG, EXIF, XMP or IPTC specifications that
states an individual Creator string may not contain a semicolon, and for
this to be feasible all of these specifications would require this
restriction.) For this reason, the MWG:Creator tag is written as a single
string. Multiple names may of course be written within the string (and it
would be reasonable to separate them with semicolons as suggested by the MWG
and EXIF specifications), but this tag is not treated as a list by ExifTool
when writing.</p>
<p>Another potential stumbling block for MWG compatibility is the fact that
ExifTool will quite happily read and write (but not create) EXIF, IPTC and
XMP which has been stored in non-standard locations while the MWG
recommendation states that this metadata should be ignored. This may lead
to non-compliant behaviour for these types of files.</p>
<blockquote>
<table class=frame><tr><td>
<table class=inner cellspacing=1>
<tr class=h><th>Tag Name</th>
<th>Writable</th><th>Derived From</th><th>Values / <span class=n>Notes</span></th></tr>
<tr>
<td>City</td>
<td class=c>Y</td>
<td class=n>IPTC:City
<br>XMP-photoshop:City
<br>CurrentIPTCDigest
<br>IPTCDigest</td>
<td> </td></tr>
<tr class=b>
<td>Copyright</td>
<td class=c>Y</td>
<td class=n>EXIF:Copyright
<br>IPTC:CopyrightNotice
<br>XMP-dc:Rights
<br>CurrentIPTCDigest
<br>IPTCDigest</td>
<td> </td></tr>
<tr>
<td>Country</td>
<td class=c>Y</td>
<td class=n>IPTC:Country-PrimaryLocationName
<br>XMP-photoshop:Country
<br>CurrentIPTCDigest
<br>IPTCDigest</td>
<td> </td></tr>
<tr class=b>
<td>CreateDate</td>
<td class=c>Y</td>
<td class=n>EXIF:CreateDate
<br>EXIF:SubSecTimeDigitized
<br>IPTC:DigitalCreationDate
<br>IPTC:DigitalCreationTime
<br>XMP-xmp:CreateDate
<br>CurrentIPTCDigest
<br>IPTCDigest</td>
<td><span class=s><span class=n>("creation date of the digital representation" - MWG)</span></span></td></tr>
<tr>
<td>Creator</td>
<td class=c>Y</td>
<td class=n>EXIF:Artist
<br>IPTC:By-line
<br>XMP-dc:Creator
<br>CurrentIPTCDigest
<br>IPTCDigest</td>
<td><span class=s><span class=n>(NOT a list-type tag. See "A problem with the MWG specification" above)</span></span></td></tr>
<tr class=b>
<td>DateTimeOriginal</td>
<td class=c>Y</td>
<td class=n>EXIF:DateTimeOriginal
<br>EXIF:SubSecTimeOriginal
<br>IPTC:DateCreated
<br>IPTC:TimeCreated
<br>XMP-photoshop:DateCreated
<br>CurrentIPTCDigest
<br>IPTCDigest</td>
<td><span class=s><span class=n>("creation date of the intellectual content being shown" - MWG)</span></span></td></tr>
<tr>
<td>Description</td>
<td class=c>Y</td>
<td class=n>EXIF:ImageDescription
<br>IPTC:Caption-Abstract
<br>XMP-dc:Description
<br>CurrentIPTCDigest
<br>IPTCDigest</td>
<td> </td></tr>
<tr class=b>
<td>Keywords</td>
<td class=c>Y+</td>
<td class=n>IPTC:Keywords
<br>XMP-dc:Subject
<br>CurrentIPTCDigest
<br>IPTCDigest</td>
<td> </td></tr>
<tr>
<td>Location</td>
<td class=c>Y</td>
<td class=n>IPTC:Sub-location
<br>XMP-iptcCore:Location
<br>CurrentIPTCDigest
<br>IPTCDigest</td>
<td> </td></tr>
<tr class=b>
<td>ModifyDate</td>
<td class=c>Y</td>
<td class=n>EXIF:ModifyDate
<br>EXIF:SubSecTime
<br>XMP-xmp:ModifyDate
<br>CurrentIPTCDigest
<br>IPTCDigest</td>
<td><span class=s><span class=n>("modification date of the digital image file" - MWG)</span></span></td></tr>
<tr>
<td>Orientation</td>
<td class=c>Y</td>
<td class=n>EXIF:Orientation</td>
<td><span class=s>1 = Horizontal (normal)
<br>2 = Mirror horizontal
<br>3 = Rotate 180
<br>4 = Mirror vertical
<br>5 = Mirror horizontal and rotate 270 CW
<br>6 = Rotate 90 CW
<br>7 = Mirror horizontal and rotate 90 CW
<br>8 = Rotate 270 CW</span></td></tr>
<tr class=b>
<td>Rating</td>
<td class=c>Y</td>
<td class=n>XMP-xmp:Rating</td>
<td> </td></tr>
<tr>
<td>State</td>
<td class=c>Y</td>
<td class=n>IPTC:Province-State
<br>XMP-photoshop:State
<br>CurrentIPTCDigest
<br>IPTCDigest</td>
<td> </td></tr>
</table></td></tr></table></blockquote>
<hr>
(This document generated automatically by Image::ExifTool::BuildTagLookup)
<br><i>Last revised Oct 28, 2009</i>
<p class=lf><a href='index.html'><-- ExifTool Tag Names</a></p>
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