The Measurement Calculus
  We propose a calculus of local equations over one-way computing patterns, which preserves interpretations, and allows the rewriting of any pattern to a standard form where entanglement is done first, then measurements, then local corrections. We infer from this that patterns with no dependencies, or using only Pauli measurements, can only realise unitaries belonging to the Clifford group. 
Vincent Danos, Elham Kashefi and Prakash Panangaden