Pending heat vs Heating, Pearl t-stat

My t-stat will be in Pending heat mode(it actually IS heating) until I turn the fan to ON, then it is in Heating mode. What is Pending Heat mode supposed to do?

I have a Pearl with a "boiler" heating system (aka baseboard heat). Of course i have no fan.
My Pearl also says "pending heat", and during "pending heat" the Pearl tells the boiler to generate heat (aka turn on).

From your observation I would guess in a hot air system the call for heat will be delayed until the fan comes on, hence the "pending Heat".

However I just turned the fan on (in the device page). The status of my system is not shown as "fan only". So I guess I don't know......

Related:
In another thread @mike.maxwell mentioned he received a whole set of Centralite devices and planned to work on their drivers. Perhaps we will be getting a driver specifically for the Pearl.

I have a gas furnace setup, and mine always says pending heat when it's running too.