The standard metadata format should be modified in the following ways:

Add two enumerated values to the "name" attribute of the "ColorSpaceType"
node, "PhotoYCC" and "YCCK".

Make the value attribute of the HorizontalPixelOffset node an integer
Make the value attribute of the VerticalPixelOffset node an integer

Add two new nodes under "Dimension":

  HorizontalScreenSize, contains integer attribute "value"
  VerticalScreenSize, contains integer attribute "value"

Add new node under "Document"

  FormatVersion, contains String attribute "value"

Add default values to some attributes:

  Attribute "hour" of node ImageModificationTime, default value 0
  Attribute "minute" of node ImageModificationTime, default value 0
  Attribute "second" of node ImageModificationTime, default value 0
  Attribute "hour" of node ImageCreationTime, default value 0
  Attribute "minute" of node ImageCreationTime, default value 0
  Attribute "second" of node ImageCreationTime, default value 0