All the comparison functions request a horizontal and a vertical sequence and the ranges over which the function will operate. It is therefore possible to compare the same sequence over different ranges. The default sequences which appear when the dialogue box for the comparison function is brought up, are the current "active" sequences ( see section Sequence manager). To select a different sequence for this invocation of the function, press the Browse button to the right of the "Seq identifier" box. This will invoke a Sequence manager if one is not already displayed. Clicking with the left mouse button on the name of the required sequence in the sequence manager will update the function dialogue box with the sequence name and it's currently defined range. To change the range, enter the new start and end positions. These positions will be remembered for future invocations of any of the comparison functions for this sequence.