I was considering some of the changes with Haystack4 versus the way I have used tags in the past (albeit sometimes improperly).

I use the directZone tag to mark all equipment that directly controls zone conditions. This makes an easy way to query all equipment responsible for zone control and analyze their effectiveness. This could include VAV Terminals, FCUs, AHUs, and others. But what it excludes is any equipment with sub-zones that do not directly control the zone conditions. This is a grouping that is often done and can be challenging by any other method.

I believe this could easily be achieved by modifying the ahuZoneDeliveryType to zoneDeliveryType and allow it to be used on any airHandlingEquip or airTerminalUnit.

Thoughts

I used an explicit name including "ahu" for that guy because it seemed really specific for AHUs. Based on your usage, I don't think the other choices chilledBeamZone, multiZone, or vavZone make sense to they? Seems like maybe a separate tag

Note that a tag such as directZone can actually subtype from multiple choices, although we've been trying to avoid that