“…The role of RNA is largely determined by its tertiary structure and the comparison of 3D RNA structures is, thus, an effective tool for studying RNA function and evolutionary relationships. Several methods and servers for pairwise RNA structure comparison and alignment exist, including ARTS [ 8 , 9 ], DIAL [ 10 ], iPARTS [ 11 ], SARA [ 12 , 13 ], SARSA [ 14 ], Rclick [ 15 , 16 ], R3Dalign [ 17 , 18 ], RASS [ 19 ], FRASS [ 20 ], SETTER [ 21 , 22 ] or R3D-BLAST [ 23 ]. The extension of a pairwise alignment to the simultaneous alignment of several structures is called a multiple structure alignment.…”