Effects: It is 
implementation-defined whether the sequence pointers in 
*this
(
eback(), 
gptr(), 
egptr(),
pbase(), 
pptr(), 
epptr()) obtain
the values which 
rhs had
.  Whether they do or not, 
*this
and 
rhs reference separate buffers (if any at all) after the
construction
.Additionally 
*this references the file
which 
rhs did before the construction, and
rhs references no file after the construction
.The
openmode, locale and any other state of 
rhs is also
copied
.