assembly - What does brace "{" mean in AT&T assembly

Question

I am using Intel Xeon Phi. I compile the program like

icpc -mmic -S xxxx.cpp

There are some syntax I don't understand in the assembly code.

     vgetmantpd $0, %zmm2, %zmm9{%k3}                        #85.59 c79
     vsubpd    %zmm11, %zmm10, %zmm12{%k3}                   #85.59 c83
     vpminsd   %zmm14{aaaa}, %zmm12, %zmm13                  #85.59 c87
     vcvtpd2ps {rz-sae}, %zmm9, %zmm6{%k3}                   #85.59 c91
     vpminud   %zmm14{bbbb}, %zmm13, %zmm15                  #85.59 c95

What does the "{"/"}" mean in %zmm12{%k3}. And what is %k3? What is %zmm14{bbbb} ?