CFD Online Discussion Forums - Lack of understanding? Spatial OF Schemes

Hi guys,

i just want to ask a simple question, I heard often that OF is 2nd order in spatial and time.

Higher order in time: Possible, implementing Runge-Kutta

Higher order spatial:
If I have a look at the numerical schemes of OpenFoam on this side:
http://openfoam.org/docs/user/fvSchemes.php

For those terms is always a fourth order interpolation scheme existing:
interpolationSchemes
snGradSchemes
gradSchemes Gradient http://openfoam.org/docs/user/img/user373x.png divSchemes Divergence http://openfoam.org/docs/user/img/user374x.png laplacianSchemes Laplacian http://openfoam.org/docs/user/img/user375x.png
This means that the reconstruction of the flux could be done by 4th order polynomials (bounded or unbounded) for all NS Eq Terms .

So this must be 4th order in space, or do I miss something really important?

Thanks to you

In addition to that:
How can I use the fourth order schemes in correct way? I got always the error that the fourth order schemes are unknown

Code:

gradSchemes

{

    default         none;

    grad(p)         Gauss fourth;

}



divSchemes

{

    default         none;

    div(phi,U)      Gauss fourth;        

}



laplacianSchemes

{

    default         none;

    laplacian(nu,U) Gauss fourth;

    laplacian((1|A(U)),p) Gauss fourth;

}



interpolationSchemes

{

    default         none;

    interpolate(HbyA) cubicCorrection;

}



snGradSchemes

{

    default         fourth;

}



fluxRequired

{

    default         no;

    p               ;

}