  We investigate some issues that are relevant for the derivation of
experimental limits on the parameters of canonical noncommutative spacetimes.
By analyzing a simple Wess-Zumino-type model in canonical noncommutative
spacetime with soft supersymmetry breaking we explore the implications of
ultraviolet supersymmetry on low-energy phenomenology. The fact that new
physics in the ultraviolet can modify low-energy predictions affects
significantly the derivation of limits on the noncommutativity parameters based
on low-energy data. These are, in an appropriate sense here discussed,
``conditional limits''. We also find that some standard techniques for an
effective low-energy description of theories with non-locality at short
distance scales are only applicable in a regime where theories in canonical
noncommutative spacetime lack any predictivity, because of the strong
sensitivity to unknown UV physics. It appears useful to combine high-energy
data, from astrophysics, with the more readily available low-energy data.
