Confused about groups versus levels

UPDATE: never mind. I was only using omnioutliner for this because I had come to dislike omnifocus. But while I was on the site, I noticed the new omnifocus was available, so I snagged it. It’s really much better, so it would be a mistake to use omnioutliner for what I am trying to do. Although I suppose I’d still be curious about the questions I asked, if there is a concise answer to them somewhere.

I’m setting up an outline for work needed to do some equipment upgrades in my lab. I want to have a duration column for individual chunks of work, so I can get an idea of how long various higher-level chunks will take. At this point, the outline has three levels, but this could increase as I continue to plan. Logically, only terminal nodes (rows with no subrows) would have a fixed duration; parent (and grand…parent) nodes’ durations should be the recursive sum of lower elements.
But when I tried to make this happen, it didn’t, so I RTFM. It appears that ordinary parent nodes don’t get sums, only parents of groups. So before I go on with this, I’d like to know two things I couldn’t find in the manual: (1) Can you convert a top-level ordinary parent into a group (i.e., using the ordinary parent node as the parent of a new group)? I believe that this would be the reverse of what happens when you ungroup. (2) Can you have subgroups? I.e., can a duration column in a level 2 row be filled with the sum of its level 3 subrows, by somehow using the group feature? It would seem that this would have to be true if the summarizing process is to be recursive in any useful sense of the term.

I’m glad that you’re happy with OmniFocus 2, but I’ll still try to address your questions anyway:

A “group” is just a parent row and all of its descendants. So there is no conversion necessary; if you enable summaries on a column, every row that has children will have a summary value in that column. OmniOutliner will draw that cell with a gray background to indicate that its value cannot be edited.

Ah, now that you explain it so clearly, I easily made it work. Thanks for that. But now I have to decide whether to use OmniOutliner or OmniFocus (just kidding, I’m sticking with OmniFocus for this project).

Maybe it’s just me, but the user guide confused me on this point. The key to me was your explanation that a group and a hierarchy of levels are the same kind of thing.