You are right, values 1 to 968 are speed traps, or records going all the way around the track. Value 1 represents the start of a new lap and value and 968 is when a car crosses the S/F to end a lap.
I'm guessing the AI start their entry onto pitlane around record 850 and exit the pits around record 109, you'll notice the speeds gradually increasing again.
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More on SPEED, POSITION & CORIOLIS by Robert Szikszo copied from his EDIT45 readme:
SPEED:
The SPEED graph simply shows the ideal speed in [mph], which AI-cars try
to reach at that point of the racetrack; if it is too much in a corner
they maybe spin out. Here you can edit the AI-cars' acceleration.
POSITION:
The POSITION graph shows the transversal position in [ft] of car on the
track. The more positive position means that car drives on the left, and
more negative position means that car drives on the right from the center-
line. On an ideal track, the zero position should be represent the
centerline. BUT THERE ARE ONLY A FEW TRACKS OF ALL WHICH ARE IDEAL!
If this graph is nearly constant, the car drives on a straight line. If
this looks something like a sinus wave, the car is probably in a long
corner, or just changing the side to prepare for the next corner . If the
sinus wave is transferred to a narrow peak, the car is probably in a
sharp corner. The corner's type mainly depends on the actual speed values.
A left-hand corner is a "hill", and a right-hand corner is a "valley" in
the graph. You should know well enough the tracks to identify what kind of
moving you see on this graph; the best would be if you had a track-map.
A good cornering produces a nice sinus wave in the graph (car moving
from one side of the track to the inside of the corner, and back).
CORIOLIS:
The CORIOLIS graph shows the coriolis force, probably. It is positive
when car comes closer to the centerpoint of a corner, and negative when
car moves farther from it. In straights, this value should be zero, or
unsignificantly low. I THINK these values do NOT need updating, but I have
created a function - called ACC (Automatic Coriolis Correction), which
can calculate out the right coriolis value from the position and speed
datas by pressing the <ALT> + <A> keys.