DMF Developed Software: BL (Blinkenlichten)
Once set to a certain Y-axis position, the LEDs change from yellow to red, depending on how far off the transect (up or down) the operator had wandered. This allowed interesting objects to be investigated, but then return to the original path along the Y-axis, thus ensuring linear transects and complete coverage of the specimen surface if desired. The arrows on the only button on the main interface (which sets the current Y-axis position as the transect center) also serves as a reminder as to which direction the transect is proceeding.
Since tolerance to Y-axis deviations varies with magnification, a context menu allows setting working magnification and yellow/red tolerances:
Recently an optional "Map Location" function was added, showing operators where they are on the specimen (and where they've been):