-On some
-.Pq non- Ns Tn UNIX
-systems an
-.Dq Fa fpos_t
-object may be a complex object
-and these routines may be the only way to portably reposition a text stream.
+These functions provide a portable way to seek to offsets larger than
+those that can be represented by a
+.Vt long int .
+They may also store additional state information in the
+.Vt fpos_t
+object to facilitate seeking within files containing multibyte
+characters with state-dependent encodings.
+Although
+.Vt fpos_t
+has traditionally been an integral type,
+applications cannot assume that it is;
+in particular, they must not perform arithmetic on objects
+of this type.