nacmei lujvo

x1 is a vector of dimension x2 with coordinates x3, x4, x5, ...

See also relnacmei, cibnacmei, pinynacmei, rajnacmei, nacmemsu'a

In notes:

cibnacmei
x1 is a 3-dimensional vector with coordinates x2, x3 and x4.
relnacmei
x1 is a 2-dimensional vector with coordinates x2 and x3.