The label window appears when clicking on the Label Tool:
This allows text labels to be assigned to outlines. The menu bar allows saving and loading of label names in the "File" menu and the addition of new labels using the "Label" menu. If the check box "Assign current label when extracting" is active, when you press "e" to extract a contour into an outline, the current label will be assigned to the new outline.
In the example shown above, the currently selected label is "Caudate" and the words "Right" and "Left" will automatically be included depending on where the outlines are in the image (assuming that the "MID_SAGITTAL_POINT" landmark has previously been set). Clicking on "Caudate" will bring up a list of other labels to choose from.
The "Next" and "Previous" buttons can be used to review the labels of each outline in the current slice.
When creating a new label (using the "Label:New" menu), you can set the text of the label, choose if it should automatically assign "Left" and "Right" and also decide what color its outline should be filled with.