Allows you to scroll forward or backward through a graph of a trend tag's history. To switch into History Mode, select the Display History Mode checkbox. The display changes to lower version of the control shown to the left.
The four buttons allow you to move backwards or forwards through the trend graph, with the two outer buttons shifting a page at a time, and the two inner buttons shifting half a page. The clock icon allows you to edit the end time for the historical display.
Deselecting the box returns to the normal trend view.