[boost] <iostream> and std::endl

progress.hpp uses std::endl and includes only <iostream> I read the following at http://groups.google.com/group/comp.lang.c++/browse_thread/thread/ef96516cd91b8ee1/6a50ad170b176f50?lnk=st&q=iostream+endl&rnum=1#6a50ad170b176f50 "Note: while most implementations will work without it, the declaration for 'endl' is provided by <ostream>. It is allowed to be, but not required to be, provided by <iostream>. 'endl' is also in namespace 'std'. (Its 'full name' is 'std::endl')" Shouldn't <ostream> be included?