By default, the Process Analyst locks together the time span and position in time (horizontal axis) of every pen. However, you can unlock the pens, allowing the pens to be displayed across different positions in time and/or time spans.
For example, you could unlock pens to compare a previous month's data for a tag with the data for this month. You would do this by adding two pens to a pane that represent the same tag, then unlocking the pens, and adjusting the time positions for each pen as necessary.
To control pen locking and unlocking, you use the Lock/Unlock Pens button on the main toolbar.
This option is also available on the right-click (context) menu.
Locking and unlocking has the following behavior:
When transitioning from locked to unlocked, the time span and position in time of every pen are synchronized to match that of the primary selected pen.