Hi, all, Why are there so many .so and .a files in $BOOT_HOME/lib? Take boost_singal as an example, there are about a dozen . They are: libboost_signals-gcc-1_32.a libboost_signals-gcc-1_32.so libboost_signals-gcc.a libboost_signals-gcc.so libboost_signals-gcc-d-1_32.a libboost_signals-gcc-d-1_32.so libboost_signals-gcc-mt.a libboost_signals-gcc-mt-d-1_32.so .... I wonder what are 'd' and 'mt' mean? "debug" and "mutil-thread"? If so, i wonder when i use a 'mt' thread , e.g. libboost_signals-gcc-mt-d-1_32.so, will i have to use -pthread for Linux and -pthreads for Solaris along with my other g++ compile options. Why? Another, for stdc++.so, are there two versions , each for 'mutil-thread' and 'sigal-thread' support? What's the relationship between these versions and the compiler options like '-pthread' ? BR. /TomTan