rgument<br><br>

<li> It is now possible to construct a <tt>RooSimultaneous</tt> p.d.f. from other
     <tt>RooSimultaneous</tt> p.d.f.s, provided the constructor form is used that takes
     all input p.d.f.s. In this constructor simultaneous-of-simultaneous p.d.f.s are automatically
     recast to an equivalent top-level simultaneous p.d.f
     Sim of sim now possible<br><br>

<li> Several improvements were made in the internal handling of datasets that
     will speedup certain data intensive operations<