  Looking at the orbits of small bodies with large semimajor axes, we are
compelled to see patterns. Some of these patterns are noted as strong
indicators of new or hidden processes in the outer Solar System, others are
substantially generated by observational biases, and still others may be
completely overlooked. We can gain insight into the current and past structure
of the outer Solar System through a careful examination of these orbit
patterns. In this chapter, we discuss the implications of the observed orbital
distribution of distant trans-Neptunian objects (TNOs). We start with some
cautions on how observational biases must affect the known set of TNO orbits.
Some of these biases are intrinsic to the process of discovering TNOs, while
others can be reduced or eliminated through careful observational survey
design. We discuss some orbital element correlations that have received
considerable attention in the recent literature. We examine the known TNOs in
the context of the gravitational processes that the known Solar System induces
in orbital distributions. We discuss proposed new elements of the outer Solar
System, posited ancient processes, and the types of TNO orbital element
distributions that they predict to exist. We conclude with speculation.
