1. A data processing system for summarizing textual data of a document, the data processing system comprising: a bus; a memory connected to the bus, wherein the memory comprising computer-executable instructions; a processor unit connected to the bus, wherein the processor unit executes the computer-executable instructions to direct the data processing system to: retrieve a given rule from a rule database comprising a plurality of rules that each specify textual characteristics for various types of the textual data and an associated icon; analyze the textual data of the document using the given rule to form a respective matching index value; repeat the retrieve and analyze actions for each rule of the plurality of rules; select at least one of the plurality of rules whose specified textual characteristics match characteristics of the textual data by comparing each respective matching index value to a threshold value to form selected rules; and generate a list of at least one icon according to the selected rules in order to depict at least one meaning of the document in graphical form such that each icon in the list is associated with a given one of the selected rules.