  We examine the scaling properties of an evolving network of strings in
Minkowski spacetime and study the evolution of length scales in terms of a
3-scale model proposed by Austin, Copeland and Kibble (ACK). We find good
qualitative and some quantitative agreement between the model and our
simulations. We also investigate small-scale structure by altering the minimum
allowed size for loop production E_c. Certain quantities depend significantly
on this parameter: for example the scaling density can vary by a factor of two
or more with increasing E_c. Small-scale structure as defined by ACK disappears
if no restrictions are placed on loop production, and the fractal dimension of
the string changes smoothly from 2 to 1 as the resolution scale is decreased.
Loops are nearly all produced at the lattice cut-off. We suggest that the
lattice cut-off should be interpreted as corresponding to the string width, and
that in a real network loops are actually produced with this size. This leads
to a radically different string scenario, with particle production rather than
gravitational radiation being the dominant mode of energy dissipation. At the
very least, a better understanding of the discretisation effects in all
simulations of cosmic strings is called for.
