ffc ffb ffa fdg feg ffg lxyz nxyz mxyz {abc,def} {abc} {a,b,c,d,e} x} y} {a} b} c} x,y {abc} trie /usr/ucb/ex /usr/ucb/edit /usr/lib/ex /usr/lib/how_ex XXXX{a,b,c} XXXXa XXXXb XXXXc {} { } } { abcd{efgh foo 1 2 bar foo 1 2 bar foo 1 2 bar