Methods and systems provide a "tree view" for a markup language referred to as Reusable Data Markup Language ("RDML"). Generally, a tree view comprises the components necessary for automatically manipulating and displaying a graphical display of numerical data contained in RDML markup documents. RDML is a markup language, such as the Hypertext Markup Language ("HTML") or the Extensible Markup Language ("XML"). Generally, RDML facilitates the browsing and manipulation of numbers, as opposed to text as in HTML, and does so by requiring attributes describing the meaning of the numbers to be attached to the numbers. Upon receiving RDML markup documents, the tree view transforms, formats, manipulates and displays data stored in the markup documents using the attributes describing the meaning of the data. The tree view uses the attributes of the numbers to, for example, facilitate the simultaneous display of different series of numbers of different types on a single display. It automatically displays the relationship between series of numbers while displaying appropriate labels, titles, number precision, etc. A tree view may be a component of a data viewer used to retrieve, manipulate, and view documents in the RDML format.