Sequence check box

What does the “Sequence” check box do on the task detail? I’ve tried checking it and uncheck to determine if it actual does anything and I don’t see a difference. Intuitively I thought it would be the control option to determine if any subtasks of that action would be done in a sequential order (check box - checked) or could be done in non sequential order (check box not checked). But I didn’t see a difference when I experimented with it.

Thank you.

It operates on “subprojects” (tasks with subtasks) and forces the “subproject” as a whole into a state of “sequential hold”. In other words, its tasks will not be shown on any of the active GTD lists (Next, Waiting etc) until its sibling subprojects have been completed. In other words, it is the equivalent of Forced Next.

In essence, I think this is very good. It allows you to have some subprojects active and the rest on “auto-sequential”, becoming active one at a time automatically, just as you can for actions within a project.

What I do not understand is why there is no visual marker for it (e.g. green/gray) or why there are two entirely different toggles for actions and projects for the same kind of thing (parallel/sequential control). In my opinion, the simplest and most intuitive would be to have only the Sequential toggle for items at all levels, and to indicate its status with the green/gray toggle - in other words fuse the Sequential and Forced Next toggles into one single feature.