Variogram model 3D

hi,

Excuse my ignorance, but I've read the help of the function vgm in
package gstat and still do not understand how to change the vertical
range of the variogram model in 3D, as is possible in gslib (i.e. vmodel
and kt3d).

Thank you,

Tiago Vieira.

hypothetical examplein gslib:

                  Parameters for KT3D
                  *******************

START OF PARAMETERS:
data3D.dat                         \file with data
0   1   2   3    4     0         \   columns for DH, X, Y, Z, var, sec var
-1.0e21   1.0e21                 \   trimming limits
0                                \option: 0=grid, 1=cross, 2=jackknife
xvk.dat                          \file with jackknife data
1   2   0    3    0              \   columns for X,Y,Z,vr and sec var
3                                \debugging level: 0,1,2,3
kt3d.dbg                         \file for debugging output
teste3D.out                      \file for kriged output
51    0.0    2.0                 \nx,xmn,xsiz
51    0.0    2.0                 \ny,ymn,ysiz
51    0.0    2.0                 \nz,zmn,zsiz
1    1      1                    \x,y and z block discretization
4    8                           \min, max data for kriging
0                                \max per octant (0-> not used)
60.0  60.0  60.0                 \maximum search radii
 0.0   0.0   0.0                 \angles for search ellipsoid
1     2.302                      \0=SK,1=OK,2=non-st SK,3=exdrift
0 0 0 0 0 0 0 0 0                \drift: x,y,z,xx,yy,zz,xy,xz,zy
0                                \0, variable; 1, estimate trend
extdrift.dat                     \gridded file with drift/mean
4                                \  column number in gridded file
1    0.0                         \nst, nugget effect
1    3.0    0.0    0.0    0.0    \it,cc,ang1,ang2,ang3
           40.0   40.0    0.0    \a_hmax, a_hmin, a_vert