+A layer consists of a collection of items, listed in the order in which
+they should be drawn
+(from bottom-most to top-most).
+Up to version 0.3.3, the only legal contents within a layer are
+strokes. The format of a stroke is:
+<pre><stroke tool="..." color="..." width="...">
+... list of coordinates ...
+</stroke>
+</pre>
+The <i>tool</i> attribute can take the values "pen", "highlighter", or
+"eraser" depending on the tool used to create the stroke (pen, highlighter,
+or whiteout eraser); a value of "highlighter" indicates that the stroke
+should be painted in a partially transparent manner (Xournal uses an alpha
+coefficient of 0.5).
+</p>
+<p>
+The <i>color</i> attribute can take one of the standard values "black",
+"blue", "red", "green", "gray", "lightblue", "lightgreen", "magenta",
+"orange", "yellow", "white", or can specify a hexadecimal RGBA value in
+the format "#rrggbbaa".
+</p>
+<p>
+The <i>width</i> attribute is a floating-point
+number (or a sequence of floating-point numbers starting with version 0.4.2),
+and specifies the width of the stroke in points (1/72 in). (For a
+variable-width stroke, the <i>width</i> attribute contains a
+whitespace-separated succession of floating-point values: first the
+nominal brush width, and then the width of each successive segment forming
+the stroke.)
+</p>
+<p>
+The list of coordinates is simply a succession of floating-point values,
+separated by whitespace.
+The number of given values must be even; consecutive pairs of values give
+the <i>x</i> and <i>y</i> coordinates of each point along the stroke.
+These values are expressed in points (1/72 in). The coordinates (0,0)
+represent the top-left corner of the page: hence x is measured from the left
+of the page, and y is measured from the top of the page.
+</p>
+<p>
+Every stroke must contain at least two points (four floating point values).
+Moreover, two consecutive points on the stroke should be spaced no more
+than 5 units apart or so; longer line segments should be subdivided as
+appropriate (otherwise the eraser tool will not interact properly with the
+stroke). The default precision used by Xournal for the x,y coordinates is
+0.01 unit (1/7200 in).
+</p>
+<p>Starting with version 0.4, layers also contain text items.
+The format of a text item is:
+<pre><text font="..." size="..." x="..." y="..." color="...">... text ...</text>
+</pre>
+The <i>font</i> attribute contains the font name, for example "Serif Bold
+Italic"; if the font is not available, another font will be substituted.
+The <i>size</i> attribute specifies the font size in points. The <i>x</i>
+and <i>y</i> attributes specify the coordinates of the top-left corner
+of the text box in page coordinates (measured in points from the top-left
+corner of the page). Finally, the <i>color</i> attribute contains either
+the name of a standard color or a hexadecimal RGBA value (see above).
+</p>
+<p>
+The contents of the text are encoded in UTF-8, with the characters
+<tt>'&', '<', '>'</tt> replaced by <tt>&amp;, &lt;,
+&gt;</tt>. Whitespace and linefeeds are preserved (in particular,
+no extraneous whitespace should be inserted between the enclosing tags
+and the text itself).