Martin Audio W8L Longbow Application Manual page 48

Note that the top front edge of the upper cabinet is the distance reference point. This is
indicated as a blue vertical line on the view which indicates the datum point
Array
from which coverage Start/Stop distances are measured.
Pick Points and Cabinet Positions
Two grid pick points (front & rear) are shown for flown arrays.
All material © 2007. Martin Audio Ltd. Subject to change without notice.