What I am referring to as the "work area" is more properly called the "client area" in program terms. I'll inevitably be using both names here, but you'll know I'm talking about the same thing. Naming rites aside, this is the large area of BINedit where things actually happen.
A program's client area is the area it uses to draw on and display things - text, pictures, a bunch of lines and shapes, etc. In BINedit, this is where the program displays the currently loaded model.
BINedit's client area is displayed divided into quadrants (unless you've toggled the Show Only 3D View mode on). Each quadrant displays a different view of the current model. Let's load MTM2's Bigfoot.bin as an example.
Here we can see that in the top left quadrant, we have a side view of a vector wireframe diagram of Bigfoot - this is showing an outline of the polygonal faces that make up the model. Similarily in the bottom left we have a view of the top of the model, and in the bottom right we have a view facing it. In the top right we have a 3D view of the model, which we can rotate and switch modes to get a different view of our model.
Recall our diagram of the X, Y and Z axes from earlier:
You can see the same axes in the top right 3D view in BINedit (they can be toggled on and off as desired). Each of the other three quadrants corresponds to a view along one of these axes - we are looking along the X axis in the top left quadrant (I will call this the X View), looking down the Y axis in the bottom left quadrant (Y View), and looking along the Z axis in the bottom right quadrant (Z View).
The result of this is to give us a view from the right side of the model in the X View and a top-down view in the Y View. It is tempting to see the Z View as a look from the front of the model, but this view is actually from the rear - the transparency of the wireframe can make this confusing.
You can also see that the program displays the current face and vertex number at the bottom of the top right quadrant. -1 indicates that no face/vertex is selected; face and vertex numbers begin at 0 and increase from there (1, 2, 3...).
Here I've rotated the 3D view of the model, and zoomed in a little to get a different look at it. I've also selected a face and a vertex - you can see the numbers displayed at the bottom of the 3D view. The face I've selected (number 51, as it happens) is part of the truck's hood - you can see it tinted pink in the 3D view, and outlined in white on the other three wireframe views. The currently selected vertex (number 3) is on the tailgate of the truck - you can see BINedit has drawn a second set of X, Y and Z axes centred on that vertex in the 3D view, and placed a small white and red dot on the wireframe views.
Tagged vertices and faces appear differently. A tagged face turns tinted green in the 3D view and its outline also changes from white to green on the wireframe views. As an example, here I have tagged all the faces on Bigfoot's hood:
Tagged vertices are not shown on wireframe views, but they are visible on the 3D view as large black dots (but only if Show Vertices in 3D View is toggled on). Here, I have tagged all the vertices on Bigfoot's bumper:
There will be more on faces and vertices later, but for now, let's leave it at that - we know how the program utilises its available display space and the basics of how it displays a model.