Hexagonal lattices and Miller-Bravais indices

Similarly, planes with Miller indices (110) are identical to (110) planes. 

In lattices of high symmetry, there are always some sets of (hkl) planes that are identical from the point of view of symmetry. For example, in a cubic lattice, the (100), (010) and (001) planes are identical in every way. Similarly, in a tetragonal lattice, (110) and (110) planes are identical. Curly brackets, hkl, designate these related planes. Thus, in the cubic system, the symbol 100 represents the three sets of planes (100), (010), and (001), the symbol 110 represents the six sets of planes (110), (101), (Oil), (110), (T01), and (Oil), and the symbol 111 represents the four sets (111), (111), (111) and (111). 

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