:ELEMENT-TYPE - the type of object to read or write, default BASE-CHAR
:IF-EXISTS - one of :ERROR, :NEW-VERSION, :RENAME, :RENAME-AND-DELETE,
:OVERWRITE, :APPEND, :SUPERSEDE or NIL
:ELEMENT-TYPE - the type of object to read or write, default BASE-CHAR
:IF-EXISTS - one of :ERROR, :NEW-VERSION, :RENAME, :RENAME-AND-DELETE,
:OVERWRITE, :APPEND, :SUPERSEDE or NIL