12. A method according to claim 11, wherein said step of converting said subsequent element traces through a sub-element linked list containing said first element and a plurality of representations of said subsequent element and chooses said one of the plurality of said second representations of the subsequent element by choosing a first representation of said subsequent element which appears after said first element in said sub-element linked list.
11. 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 first element of a second representation; inputting a subsequent element of the first representation, said subsequent element having a plurality of second representations; converting said subsequent element of the first representation to one of said second representations thereof by choosing one of the plurality of said second representations of the subsequent element which is a correct sub-element for said first element.