In this edit mode character rig is represented by a set of cuboids known as Box Controllers. These box controllers can be selected and edited in the same manner as Point Controllers or any other parts of the rig.
A character in Box Controller mode
Box controllers are used for animating parts of the character that are not affected by physics. Small detais of a character model, like fingers and parts of the clothing, are convenient to adjust using box controllers. Aside from this, however, box controllers are rarely used for setting character poses, as Point Controllers are better suited for this task.
Box controllers are visible in the Box Controller mode, which can be enabled by pressing the button on the Timeline.
Fixing Box Controllers
If you try to fix selected box controllers at their positions (this can be done by pressing the R key), point controllers corresponding to them will become fixed.
To learn more about fixing controllers, see the dedicated chapter.
An example of using Box Controller mode to position character fingers
Note: The example above utilizes Tail Mode to make adjusting fingers more convenient.