[gshenaut]

(1) Not if implemented as an invariant time offset. Also, there is only one mark: how could there be a mark for invariant Overdue and for invariant Due Soon? And, the idea is for the invariant versions of those states to be treated just like the normal versions (that is, displayed with other Due Soon or Overdue objects); the mark doesn't do that. In other words, on Monday, an invariant relative time of two days in the future would be treated just like an ordinary time of Wednesday; the difference is that if nothing changed, on Tuesday, the same invariant relative time would now be treated the same as an ordinary time of Thursday.

(2) No, the difference is that tasks and projects could be linked to other tasks and other projects. Currently, only tasks within a single project can be linked in this way, as I understand it. As an example: if I were working on an application and realized that I can do a better job on them if I developed a tool, I could put them on hold in their current state until I finished the tool. When I finished the tool, all of the projects would become active again, with their schedules updated to the present. If, while building the tool, the same thing happened again--an additional tool was needed, and one or more of the tools applied to more than one current project--then you'd see the kind of cross-project dependencies that could be represented.