To overcome this inconvenience, there was developed the explicitly covariant version of light-front quantization (reviewed by Carbonell et al.), in which the state vector is defined on the light-front plane of general orientation: ω ω ⋅ ⋅ x = ω ω 0 c t − − ω ω → → ⋅ ⋅ x → → = ω ω 0 t − − ω ω x x − − ω ω y y − − ω ω z z = 0 (instead of c t + z = 0 ), where x = ( c t , x → → ) is a four-dimensional vector in the four-dimensional space-time and ω ω = ( ω ω 0 , ω ω → → ) is also a four-dimensional vector with the property ω ω 2 = ω ω 0 2 − − ω ω → → 2 = 0 . In the particular case ω ω = ( 1 / c , 0 , 0 , − − 1 / c ) we come back to the standard construction. In the explicitly covariant formulation the transformation of the reference frame and the change of orientation of the light-front plane are decoupled. All the rotations and the Lorentz transformations are purely kinematical (they do not require knowledge of the interaction), whereas the (dynamical) dependence on the orientation of the light-front plane is covariantly parametrized by the wave function dependence on the four-vector ω ω .