Model for Laps and/or Track Segments

[dret]

the current (extremely primitive) model assumes that a track may have multiple segments (a track is an array of segments, which then is an array of data points). that's based on GPX's model, where segments should be treated (i think) as potentially disconnected parts of an activity.
TCX is much more complicated: there can me multiple activities, each activity can have multiple laps, and each lap can have multiple tracks. i am not even sure it's entirely clear how to use this hierarchy (if somebody knows, please let me know!), but the main question here is: how should JTT model this?
there probably are good cases to be made for "laps" (people automatically or manually marking "segments" of their activities) and "segments" (for example, stopping the watch and restarting, potentially after moving). any preferences on how to handle this in JTT?