This option opens all elements with plus signs, to show their sub-elements, or closes all elements with minus signs to show only the top level for the entity.
To quickly display or hide all levels of elements and subelements in a record or template:
When this option is toggled on (the default), then all levels of the elements in a record or template will be displayed; if this option is toggled off, then only the first level–the entity–will be displayed.
While in a record:
This screenshot shows a record with the 'Expand/Collapse All' option toggled off (i.e., Collapse All).
For more control over the number of levels that are displayed in RIMMF, see View Menu: Expand to Level.