  Usually the only difference between relativistic quantization and standard
one is that the Lagrangian of the system under consideration should be Lorentz
invariant. The standard approaches are logically incomplete and produce
solutions with unpleasant properties: negative-energy, superluminal propagation
etc. We propose a two-projections scheme of (special) relativistic
quantization. The first projection defines the quantization procedure (e.g. the
Berezin-Toeplitz quantization). The second projection defines a casual
structure of the relativistic system (e.g. the operator of multiplication by
the characteristic function of the future cone). The two-projections
quantization introduces in a natural way the existence of three types of
relativistic particles (with $0$, $\frac{1}{2}$, and $1$ spins). Keywords:
Quantization, relativity, spin, Dirac equation, Klein-Gordon equation,
electron, Segal-Bargmann space, Berezin-Toeplitz quantization. AMSMSC Primary:
81P10, 83A05; Secondary: 81R30, 81S99, 81V45
