Changes for February 2008
=========================


List of the key changes made for the February 2008 major release of the
ome-xml data model.

The new major release of the schema has a new namespace and all version
numbers are reset to 1. As a major release, any file that validated
correctly using the last major release will probably not validate
correctly using this new release. Some files that failed to validate
before will now be valid. It is important to update any file readers and
writers to understand the changes.

The version number of all schema files is now 1.

This schema uses the new namespace:

::

    http://www.openmicroscopy.org/Schemas/[NameSpaceTitle]/2008-02/

For the OME schema

::

    http://www.openmicroscopy.org/Schemas/OME/2008-02/

and the schema file is located at

::

    http://www.openmicroscopy.org/Schemas/OME/2008-02/ome.xsd

Overview of changes
-------------------

Description (ome.xsd)
^^^^^^^^^^^^^^^^^^^^^

The ``Description`` element has become a string type. Description is not the
correct place for an XML sub-document. It has also an optional reference
to ``XML:lang`` that allows the language the Description is written in to be
recorded.

Description (AnalysisModule.xsd)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

``Description`` has been removed for ``AnalysisModule``. It is now using the
version defined in :file:`ome.xsd`.

UniversallyUniqueIdentifier for files (ome.xsd)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

To add support for splitting data across multiple OME-TIFF files in a
way that will survive file renaming, each file now has a unique
identifier. This is a ``UUID`` attribute on the ``OME`` node. It is normally
optional but is required if you wish to use multi-part files.

Multi-part OME-TIFF file support (ome.xsd)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

A TiffData block can now contain a ``UUID`` element that specifies the file
to look in for the tiff image data. The ``UUID`` element also has an
optional attribute ``FileName`` to point to the name for the file containing
the correct data. The ``UUID`` is required and the ``FileName`` is strongly
recommended. A reader should first open the file pointed to by ``FileName``.
If it does not contain the correct ``UUID`` then the reader can either fail
or search the current folder for a file that does contain the correct
``UUID``. This allows multi-part files to survive renaming.

Removal of Power attributes from Arc and Filament (ome.xsd)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

After ``Power`` was moved into ``LightSource`` in the 2007-06 V1 release, this
attribute was no longer needed in element ``Arc`` and ``Filament``. These
Power attributes should have been removed at the time. Any data can be
moved to the ``Power`` in ``LightSource``.

Simplifications (ome.xsd)
^^^^^^^^^^^^^^^^^^^^^^^^^

The types ``Correction`` and ``Immersion`` have been bundled into elements of
the same name. They were only used once in the schema. This should not
affect instance documents, only any schema derived from :file:`ome.xsd`.

Clarification of PixelTypes (ome.xsd)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The type ``PixelTypes`` has been split into two. It now has ``PixelTypes`` and
``ExtendedPixelTypes``. It was being used in two different ways in previous
schemas, once in ``Pixels`` and once in ``OTF``. Now ``Pixels`` uses
``PixelTypes`` and ``OTF`` uses ``ExtendedPixelTypes``.

AcquiredPixelsRef to AcquiredPixels (ome.xsd)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The element ``AcquiredPixelsRef`` has become attribute ``AcquiredPixels``. 
This has been changed to make ``AcquiredPixels`` consistent with the 
``DefaultPixels`` attribute in the ``Image`` element. Now both are a 
``PixelsID``.

Hash of Plane data (ome.xsd)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

There is now the option to store a SHA1 hash of a plane's image data.
This can be used to detect modification. It is stored as a ``HashSHA1``
element inside each ``Plane``. At present this is the only supported hashing
method. Others may be added in future releases.

Files with no significant changes
---------------------------------

The following files have no significant changes from the last version
released:

-  :file:`AnalysisChain.xsd`
-  :file:`BinaryFile.xsd`
-  :file:`CA.xsd`
-  :file:`CLI.xsd`
-  :file:`DataHistory.xsd`
-  :file:`MLI.xsd`
-  :file:`SPW.xsd`
-  :file:`STD.xsd`

.. note:: The file :file:`SPW.xsd` has had an import of 
          :file:`AnalysisModule.xsd` removed. This import was spurious as it 
          was not used in the file.