The discussion focuses on deriving an expression for interplanar distance using lattice parameters, particularly highlighting the simplicity of this derivation for orthogonal lattices like cubic lattices. It mentions the relationship involving the cosines of angles related to the axes, which is essential for calculating interplanar spacing. The conversation also touches on the need to expand cosines in terms of axis intercepts derived from Miller Indices. Additionally, there is a request to sketch specific planes, [110] and [222], within a cubic structure. Overall, the thread emphasizes the straightforward nature of the derivation in orthogonal geometries.