2015-09-01

*	Bug fix: The constraint for the confidence value of OCRed text was not 
	inclusive for 0.0 and 1.0 - it is now inclusive.

2013-07-15 

*	The format of polygons stored in <Coords> has been changed from 
	<Point> elements to a 'points' attribute. A polygon is now represented by a
	space separated list of points (x and y are comma separated). A list 
	requires at least two points (enforced by a regular expression constraint).
	Example: <Coords points="5,3 8,10 4,5"/>

*	All regions can now have nested sub-regions. Before this was limited to
	<FrameRegion> elements.

*	Frame regions have been removed from the schema. As a replacement
	<GraphicRegion type="frame"> can be used.

*	There are three new region types: <AdvertRegion>, <ChemRegion> and
	<MusicRegion> for advertisements, chemical formulas and musical notations.

*	The <PlainText> child element of <TextEquiv> is now optional.

*	Text recognition confidence has been introduced as new attribute of
	<TextEquiv>

*	Language can now be specified on text line and word level, in addition to
	region level. Therefore <TextLine> elements have a new attribute
	'primaryLanguage' and <Word> elements have a new attribute 'language'.
	Values set for child elements are interpreted to override values of parent
	elements.

*	The elements <Layer>, <UnorderedGroup> and <OrderedGroup> have a new attribute
	'caption'.

*	Text lines can now have a <Baseline> child element. The baseline is a multi-
	segment line represented by a list of points ('points' attribute with the same
	format and constraints as polygon points).

*	The <Page> element has a new attribute 'type'.

*	The <Page> element has a new child element <AlternativeImage> (0..*) with
	attributes 'filename' and 'comments' (to be used for bi-level image etc.).

*	New attributes 'custom' and 'comments' for various elements. The former is
	intended for machine use (custom types for instance). The latter is intended
	for human use (context information, remarks etc.).

*	Extended constraint for 'type' attribute of <GraphicRegion> element.
	Added: 'decoration', 'barcode' and 'frame'.

*	Extended constraint for 'type' attribute of <TextRegion> element.
	Added: 'endnote' and 'other'.

*	Extended constraint for 'primaryLanguage' and 'secondaryLanguage' attributes 
	of <TextRegion> element. Now conform to ISO standard.

*	Extended constraint for colour attributes.
	Added: 'other'.

*	Extended constraint for 'colourDepth' attribute.
	Added: 'other'.
	
*	The elements <TextRegion>, <TextLine>, <Word> and <Glyph> have a new child 
	element <Textstyle> with attributes 'fontFamily', 'serif', 'monospace', 
	'fontSize', 'kerning', 'textColour', 'bgColour', 'reverseVideo', 'bold',
	'italic', 'underlined', 'subscript', 'superscript', 'strikethrough',
	'smallCaps', 'letterSpaced'. Any attributes of <TextRegion> that appear
	in this list have been removed (moved to <TextStyle>).
	Values set for child text objects are interpreted to override values of parent
	text objects.

*	New attribute 'production' for elements <TextRegion>, <TextLine>, <Word> and 
	<Glyph>.
	Values set for child text objects are interpreted to override values of parent
	text objects.

*	New child element <Relations> for <Page> element to model relations between
	layout objects (e.g. drop-capital - paragraph, image - caption). Single
	relations are represented by <Relation> elements with attributes 'type',
	'custom' and 'comments' as well as two <RegionRef> child elements.