Some constructors of gp_Parab2d class contain redundant parameters

According to the theory, parabola is set by its directrix (is a simple line, not a vector) and focus point. The distances from every point of the parabola to the directrix and to the focus point are equal. The distance from the directrix to the focus point is equal to two focal length or to parameter of parabola. At that, there is a rule to direct X-axis (symmetry-axis) of local coordinate system (UCS) from the directrix to the focus point. Y-axis is always parallel to the directrix. In this case, every point of parabola is satisfied to the equation (in UCS) y(x)^2 = 2*p*x, where p is parameter of parabola.

Now, let consider existing constructors:

1. gp_Parab2d(const gp_Ax2d& D, const gp_Pnt2d& F, const Standard_Boolean Sense = Standard_True);

I do not understand, what should be the result of this constructor. Directrix D is directed line (has gp_Ax2d type). Does it mean that the direction of Y-axe should correspond to this direction? If it is not and the directrix direction is excess parameter then why we do not use gp_Lin2d class for directrix (indeed, line has direction, but it is its internal value as distinct from vector). Otherwise (if Y-direction correspond to the direction of the directrix, i.e. is defined), X-direction is defined by the directrix and the focus point (see above). Then, what is the role of "Sense" parameter? I cannot answer.

2. Constructor gp_Parab2d(const gp_Ax22d& D, const gp_Pnt2d& F).

We have analogical situation here: gp_Ax22d class sets full coordinate system XOY. Additionally, we need in focal-length only (which must be laid in positive direction of the X-axis). Why do we use focus point? More over, what kind of parabola should we obtain if the focus point does not lie in the X-axis? I cannot answer.

P.S.

Results of parabola creation for some constructor seems to be wrong. See Steps To Reproduce.