  We extend some results on piecewise linear functions on $\C^n$ to piecewise
pluriharmonic functions on any complex manifold.
  We construct a ring generated by currents $h$ and $dd^ch$, where $\{h\}$ is a
finite set of piecewise pluriharmonic functions.
  We prove that, with some restrictions on the set $\{h\}$, the map $\{h\mapsto
dd^ch,\ dd^ch\mapsto0\}$ can be continued to the derivation on the ring.
  As a corollary, the current $dd^cg_1\wedge...\wedge dd^cg_k$ depends on the
product of piecewise pluriharmonic functions $g_1,...,g_k$ only.
