Conformal Foliations and Constraint Quantization
  We show that the Classical Constraint Algebra of a Parametrized Relativistic Gauge System induces a natural structure of Conformal Foliation on a Transversal Gauge. Using the theory of Conformal Foliations, we provide a natural Factor Ordering for the Quantum Operators associated to the Canonical Quantization of such Gauge System. 
J.N. Tavares