1. A method of filtering a plurality of data items according to user input, wherein each of the data items is identified by a multiple-character identifier, the method comprising: presenting a collection of individual characters to a user, wherein any of the individual characters may be selected by the user; receiving a character sequence from the user, wherein the character sequence comprises at least one character selection selected from the collection of individual characters; for each character selection of the sequence, associating more than one character from the collection of individual characters with the character selection; and filtering the plurality of data items based on the associated characters corresponding to each character selection.