Treatment of the classical relativistic string in any orthornomal gauge

It is shown that a certain set of gauge invariant functions are, for an appropriate choice of a parameter on which they depend, equal to the Fourier components of the classical relativistic string in any orthonormal gauge. These variables are natural generalizations of the classical DDF operators recently introduced by Goddard, Hanson and Ponzano (see ibid., vol.B89, p.76 (1975)). The Poisson algebra of the relativistic string in any orthonormal gauge (including the proper time gauge) is written down. Application to quantization is briefly discussed. (12 refs).