Honeywell Vuquest 3310g User Manual page 70

In the example below, the white box is the centering window. The centering
window has been set to 20% left, 30% right, 8% top, and 25% bottom.
Since Bar Code 1 passes through the centering window, it will be read. Bar
Code 2 does not pass through the centering window, so it will not be read.
0%
10
20
30
40
50
60
70
80
90
100
0
Note: A bar code needs only to be touched by the centering window in order to
be read. It does not need to pass completely through the centering
window.
3 - 20
Bar Code 1
10 20 30 40 50 60
Bar Code 2
70 80 90 100%