What does a green LED light on a Honeywell 4219 mean?

Recently, the Honeywell 4219 printed circuit board got an upgrade, which added a few additional features. You now have the option, via dip switch, to choose whether or not you wish to use End of Line Resistors. The tamper option is now determined by a dip switch instead of a jumper, and there's a green LED that indicates...something.

The engineers decided it might be a good idea to indicate, via the green LED, whether or not the unit was receiving power. Out of the box, the dips are set to address 1, which means dip switch 2 is in the off position. So, assuming you haven't changed the dips, when you first power the unit up, the green LED will light to indicate power is present. If using the 4219 for zones 9 - 16 on a Vista panel, the address needs to be set to 7, so once again, dip switch 2 is in the off position. The green LED will continue to light to indicate power is present. So far, so good. You don't run into any issues with this until you add a second 4219 for use on zones 17 - 24. For these zones, the address of the 4219 should be set to 8, and this means dip switch 2 will be in the on position. Once dip switch 2 is on, the green LED ceases to function as a power indicator, and will remain off as long as the dip switch is on. This is as designed and does not indicate any type of issue. Per engineering, the green LED was intended to indicate power upon initial power up, and beyond that point, it ceases to be relevant.