Define analysis region 
Using this button you can draw a rectangular area on the drawing in order to define the measurements that will be included in the analysis of the current measurement sheet. Click and drag the cursor to define the region and click again to complete it. Analysis regions on the drawing are distinguished by a red dashed line.
You can define as many analysis regions as you
wish. Each region will appear in a separate tab of the analysis window. If there
is no analysis regions defined then the whole drawing is considered as one
region.
Note that, for a measurement to be included in the
analysis of a region, it must fully surrounded by the region’s rectangle.
If a measurement is included in more than one
analysis regions, it will be analyzed and appear in all of them.
You can resize an analysis region after its
creation. Click on it to select and then drag the upper-left or the lower-right
handle to change its size. Click again to complete the resizing.
You can delete a region
at any time. Click on it to select and then click the ‘Delete selected’ 
button.