[whpalmer4]

While it is true that the top level of a project must be either sequential or parallel, you can have action groups (nested actions) which are the opposite of what their containing project (or action group) is. So you can have a project which has several parallel sequences running, and some of those sequences can have spots which have parallel tasks, etc.

You can't get quite the degree of spaghetti tangles that you can with a Gantt chart with Start-Start, Start-Finish, Finish-Start, and Finish-Finish dependencies. Some might see that as a good thing :-) I find it is often better to just sketch out the first few steps in a project in detail and not worry so much about the later ones at the outset. When I've got a few of them done, then I'll sketch out a few more steps. It's pretty rare that a complex plan goes exactly as planned, so I roll with it and save the effort that would otherwise go into reworking the plan again and again.