  This paper presents a space-time-wise orthogonal analysis of space-time
crystals. This analysis provides a solution consisting of a pair of explicit
parametric equations that result from a separate application of the
Bloch-Floquet theorem in the (orthogonal) directions of space and time.
Compared to previous approaches, this solution offers the benefits of greater
simplicity, clearer emphasis on space-time duality and deeper physical insight.
