configuration files to map XML elements to graphical components. These kinds of editors are generally more useful for XML languages for data rather than for storing documents. Documents tend to be fairly free-form in structure, which tends to defy the generally rigid nature of many graphical editors. In the above example, the editor is using a configuration file to know that the TABLE element represents a table, the TR element represents a row of the table, and the TD element represents a cell of the table. It is using this information to display the table based on this structuring information, in order to make editing easier. Schema and configuration files information can also be used to ensure that users do not create invalid documents. For instance, in a text editor, it is possible to create a row with too many cells in the table, while this would not be possible with the above graphical user interface. WYSIWYG editors WYSIWYG editors let people edit files directly with the tags represented by some form of graphical viewing rather than bare XML code. Often, WYSIWYG editors attempt to emulate the end result of some transform or CSS stylesheet application. This emulation may or may not be possible, depending on the transformation from XML into the end result. Naive use of a WYSIWYG editor can lead to the creation of documents that do not have the intrinsic semantics of the particular XML language. This comes about if the user is focused on trying to achieve a certain visual presentation with the editor, rather than using the WYSIWYG to make editing the document easier. For instance, someone creating a web page could use an H2 element (meaning: second level title) instead of H1 (meaning: first level title) because it looks smaller on their current WYSIWYG editor. Such an author is making a choice based on the apparent visual representation, but a visitor to the author's web page can offer a very different rendering in their browser. However, as long as the underlying meaning of the document is understood by the author, and the author does not make decisions based on the exact look in the WYSIWYG editor, such an editor can be of value to the writer. It is generally much easier to read a document that is being rendered in some fashion than it is to read the raw XML code. Also, editing can