  We develop the theory of homogeneous Polish ultrametric structures. Our
starting point is a Fraisse class of finite structures and the crucial tool is
the universal homogeneous epimorphism. The new Fraisse limit is an inverse
limit, nevertheless its universality is with respect to embeddings and,
contrary to the Polish metric Fraisse theory of Ben Yaacov, homogeneity is
strict. Our development can be viewed as the third step of building a
Borel-like hierarchy of Fraisse limits, where the first step was the classical
setting of Fraisse and the second step is the more recent theory, due to Irwin
and Solecki, of pro-finite Fraisse limits.
