  The rest-frame instant form of the positive-energy part of the open Nambu
string is developed. The string is described as a decoupled non-local canonical
non-covariant Newton-Wigner center of mass plus a canonical basis of
Wigner-covariant relative variables living in the Wigner 3-spaces. The center
of mass carries a realization of the Poincare' algebra depending upon the
invariant mass and the rest-spin of the string, functions of the relative
variables. A canonical basis of gauge invariant Dirac observables is built with
Frenet-Serret geometrical methods. Some comments on canonical quantization are
made.
