What's the meaning of output of lsattr

I'm wondering what the output of lsattr means.It prints so oddly as follows,when I have tried: lsattr /usr. $ lsattr /usr -----------------e- /usr/local -----------------e- /usr/src -----------------e- /usr/games --------------I--e- /usr/include --------------I--e- /usr/share --------------I--e- /usr/lib -----------------e- /usr/lib32 --------------I--e- /usr/bin --------------I--e- /usr/sbin I've read the man page of chattr and lsattr but still have no idea.