Here we will describe the core of Research Description Language. How to extend this functionality is described elsewhere.
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			 The include element can be used to insert code from another 
			 document at a specified place. The src attribute contains the location of the 
			 other document. 
			 Supported formats are RDL, SVG, and 
			 MathML, as well as graphics formats
			 like JPEG. 
			
			 The experiment element does an implicit
			 include.
			
			 In the end, doing science is all about experiments that falsify or lend support to theories. 
			 For this reason, RDL makes a rather big point of using experimental data in RDL documents.
			 The experiment element is key here.
			
			 The experiment element has a src attribute that 
			 contains the location of the EDL 
			 document that describes the experiment. The dest attribute defines a 
			 conversion program that creates an RDL document from a
			 given EDL document. The resulting RDL document is then included in the referring
			 RDL document.
			
			 Note that elements containing the experiment element may affect the way the
			 conversion takes place. For example, the figure element 
			 may force a certain axis range, so that figures can be easily compared.
			
			 Figures in an RDL document are represented in Scalable Vector Graphics (SVG). That is, the 
			 figure element may contain an svg element that 
			 defines its contents. The SVG namespace 
			 (http://www.w3.org/2000/svg) is not required.
			
			 Note that one usually wouldn't want to include SVG code in an RDL document directly. Mostly
			 the SVG code will be included by an experiment 
			 element, using dest="figure".
			
			 The figure element may contain information about an axis using the 
			 axis element. Its type attribute may contain either x
			 or y. The begin and end attributes indicate the range
			 of the axis. Other usefull attributes are ticks and caption.
			 Any structure that is imposed on the figure using axis elements, is supplied
			 to the edl2rdl-figure tool, that creates SVG code from the output in an EDL
			 document, so that it can make a figure with the requested characteristics. 
			
			 One can use this feature to make figures comparable. 
			 When the compare attribute of a figure element refers to some other 
			 figure's id, the referring figure will copy the 
			 information in any axis element in the referred to figure, as well
			 as the size of the figure itself. An example is shown below:
			
<figure id="exponential" width="5cm" height="5cm"> <axis type="x" caption="Time (generations)" begin="0" end="25"/> <axis type="y" caption="Population size" begin="0" end="1400"/> <experiment src="exponential.edl" dest="figure"/> </figure> <figure compare="exponential"> <experiment src="logistic.edl" dest="figure"/> </figure>top
			 Mathematical formulas are marked up using MathML. In other words, some RDL element may contain
			 a math element that will be rendered as MathML. The MathML namespace 
			 (http://www.w3.org/1998/Math/MathML) is not required.
			
Tables are marked up using MathML as well.
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