:DIRECTION - one of :INPUT, :OUTPUT, :IO, or :PROBE
: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
+ :OVERWRITE, :APPEND, :SUPERSEDE or NIL
:IF-DOES-NOT-EXIST - one of :ERROR, :CREATE or NIL
See the manual for details."