The following was taken from a copy of the DWP:

  basic_string<charT,traits,Allocator>&
      operator=(const basic_string<charT,traits,Allocator>& str);

  Effects:
    If *this and str are not the same object, modifies *this such that:

                      Table 7--operator=(str) effects

             +-------------------------------------------------+
             | Element                    Value                |
             +-------------------------------------------------+
             |data()       points at the first element  of  an |
             |             allocated  copy  of  the  the array |
             |             whose first element is  pointed  at |
             |             by str.size()                       |
             |size()       str.size()                          |
             |capacity()   a value at least as large as size() |
             +-------------------------------------------------+
    If *this and str are the same object, the member has no effect.
  Returns:
    *this

Aside from a seeming typographical error in the Value column for Element data()
(... by str.data() ?) the wording of this seems to rule out a counted pointer
representation.

Is my interpretation correct?

--
John Hickin      Bell-Northern Research, Montreal, Quebec
(514) 765-7924   hickin@bnr.ca
---
[ comp.std.c++ is moderated.  Submission address: std-c++@ncar.ucar.edu.
  Contact address: std-c++-request@ncar.ucar.edu.  The moderation policy is
  in http://reality.sgi.com/employees/austern_mti/std-c++/policy.html. ]