Setting Up for an Attack...Question

[Captain Hill]

Some corrolary questions --

1. When using the stadimeter, is it always the last two (2) measurements that are used to calculate speed and course of the target, or does the stadimeter need to be "cleared" if the target changes course? If so, how?
2. My manual says that the speed and course buton needs to be pressed twice with a time interval in between to calculate speed and course of target. Why, then, does a single click report course and speed? Was this a manual typo? I'd have thought that it was distance and bearing (stadimeter) taken twice that'd give enough data for a speed and course.