TIFF Tag GDAL_METADATA
|Code||42112 (hex 0xA480)|
Used by the GDAL library, holds an XML list of name=value 'metadata' values about the image as a whole, and about specific samples.
Contains an XML fragment that looks like this example:
<Item name="TITLE">BV02021.CA NASA-FAO</Item>
<Item name="IMAGETYPE">13, ARTEMIS NEWNASA</Item>
<Item name="UNITS" sample="0">Meters (elevation)</Item>
<Item name="OFFSET" sample="0" role="offset">0</Item>
<Item name="SCALE" sample="0" role="scale">0.003</Item>
The <Item> names are the name of a metadata keyword, and the text contents of the Item are it's value. Normal XML escaping applies. The GDALMetadata tag may have zero or more Item sub-elements. Generally speaking the item names should be well behaved tokens (alpha-numeric + underscores) though that isn't strictly enforced. Also, normally the names are assumed to be unique.
The "sample" attribute on an Item can be used to indicate a metadata item that applies only to one sample in a multi-sample TIFF image. Sample numbering starts from 0.
The "role" attribute can be used to identify a specific semantic with a metadata item. GDAL has several specific pieces of metadata with particular interpretations and these are identified with role attributes. At a future date some of these specific roles may be documented here.
This is an unregistered tag used only by the GDAL library and applications built on it to hold Metadata about geospatial datasets.