Hi, I've slightly modified the boost/details/limits.hpp header file, for MacOS X using Project Builder. The macro __powerpc__ isn't defined. This compiler defines __ppc__ instead. ... #if defined(__sparc) || defined(__sparc__) || defined(__powerpc__) || defined(__ppc__) || defined(__hppa) #define BOOST_BIG_ENDIAN ... Now, < works without a glitch. -- FT'e