— Function: grid:codimension-one-subspace grid position index &optional destination

Select a subspace with rank one less than the argument grid. The position is a non-negative number indicating which dimension is to be dropped, and index is the fixed value it should have. If destination is specified, the result will be written to that grid.

— Function: (setf grid:codimension-one-subspace)

Set a subspace with rank one less than the argument grid. The index is a non-negative number indicating which dimension is to be dropped, and position is the fixed value it should have.