In an earlier post, Douglas Wade reviewed the basics of collapsing and expanding in Arbortext Editor. I would like to add a few thoughts about this feature as it relates to tables.
I recently started working on some SGML files that have large tables. I’m talking really large. I found that the performance of Arbortext Editor slowed considerably whenever I encountered one of these tables.
Then I received a great piece of advice: If you’re not working on tables, collapse them.
You can start by closing all of the tables in your file. Go to the View menu and select Collapse/Expand Divisions. Select the table element and click Collapse.
Now when you need to work on a specific table, expand that table, do whatever you need to do, and collapse it again when you’re done.

You can select an “expand all” option BUT is there an equivalent “collapse all” choice
Yes, The collapse button does collapse ALL. If you want to collapse only one item, place the cursor after the element, and right click and select, “Collapse Element Content”.