{@link PelTiff TIFF data} is structured as a number of Image File
Directories, IFDs for short. Each IFD contains a number of {@link PelEntry entries}, some data and finally a link to the next IFD.
function testArrayAccess()
{
$ifd = new PelIfd(PelIfd::IFD0);
$this->assertEqual(sizeof($ifd->getIterator()), 0);
$desc = new PelEntryAscii(PelTag::IMAGE_DESCRIPTION, 'Hello?');
$date = new PelEntryTime(PelTag::DATE_TIME, 12345678);
$ifd[] = $desc;
$ifd[] = $date;
$this->assertIdentical($ifd[PelTag::IMAGE_DESCRIPTION], $desc);
$this->assertIdentical($ifd[PelTag::DATE_TIME], $date);
unset($ifd[PelTag::DATE_TIME]);
$this->assertFalse(isset($ifd[PelTag::DATE_TIME]));
}
