There are two versions of model L7: model L7 and model L7s.
The structural interfaces are the same in both models. Velocity fields
in the first and in the third layer are also the same. The velocity field
in the second layer of model L7 has a vertical gradient.
The velocity field
in the second layer of model L7s is a combination of weak vertical gradient
and horizontal sinus-like function.
See the P-wave velocity sections across models L7 and L7s generated by
history file l7-grd.h.