Converters
Converters treat a StructureElement and during this process create a number of new StructureElements: the children of the initially treated StructureElement. Thus by treatment of existing StructureElements, Converters create a tree of StructureElements.
Each StructureElement in the tree has a set of properties, organized as
key-value pairs.
Some of those properties are specified by the type of StructureElement. For example,
a file could have the file name as property: 'filename': myfile.dat.
Converters may define additional functions that create further values. For
example, a regular expression could be used to get a date from a file name.