1. A method of changing a format of a file, comprising the steps of: inputting a first element having a first representation; converting said first element of the first representation to a second representation; inputting a subsequent element of the first representation; determining if a second representation of the subsequent element includes a portion which is found in the second representation of said first element; converting said subsequent element to the second representation including said portion when said determining step determines that said portion is not found in the second representation of said first element; and converting said subsequent element to the second representation without said portion when said determining step determines that said portion is found in the second representation of said first element.