  A universal code for the (positive) integers can be used to store or compress
a sequence of integers. Every universal code implies a probability distribution
on integers. This implied distribution may be a reasonable choice when the true
distribution of a source of integers is unknown. Wallace Tree Code (WTC) is a
universal code for integers based on binary trees. We give the encoding and
decoding routines for WTC and analyse the properties of the code in comparison
to two well-known codes, the Fibonacci and Elias omega codes. Some improvements
on the Elias omega code are also described and examined.
