Thank you, Geof.
I like the idea of eliminating the data movement. The original idea of the future/past waypoints was to facillitate the drawing of paths ahead of and behind a given unit. The replay feature had not yet been invented, so I was working with what I had when it did come along.
FYI, internally SimPlot tracks units by a unique identifier called UnitID. It uses a letter followed by a three digit number. For example, the first surface ship created would be S001, then S002, etc. The idea of the Track Number came in version 2 when I wanted to create a realistic way of displaying unknown units. In the real world, all detected units are assigned a TN. That and the "domain" (air, surface, subsurface, space) are the minimum information that a commander can see. The UnitID is still a part of SP2, and probably should remain as the TNs for each side may have to be unique. More thought needs to go into it.