Sections can be marked over any span of warp or weft threads. These marked sections can later be used in section assembly to generate a new WIF.
The section marker tool is on the design menu. This tool is similar to the selection tool, except that when you drag across threads a section is recorded and the section is highlighted in a color for easy identification.
The following screen shows sections marked in the threading. Hovering over one of the section, the popup shows the name of the section, and location (warp threads 19-23).
The default names of the section start with "Section" plus a number. The section can be easily renamed, deleted or modified. When hovering over the section using the section marker tool, right click to edit (see Section Editor below).
The section editor can also be accessed from section assembly by double clicked the section in the available sections area.
If you inadvertently draw a 1-thread section, it's difficult to select and right click it to remove it. Instead, click Section Assembly to view the sections and double click the section you want to delete or modify. The following example shows selecting a Weft marked section after double clicking: