How to determine if heat pump has "aux/emergency/backup" heat? | Terry Love Plumbing Advice & Remodel DIY & Professional Forum

I'd like to change the thermostat that controls an Amana heat pump because it's incredibly unintuitive. I often see the following warning on the back of many thermostat packages:

• For use on heat pumps without aux heat.

Sometimes instead of the term 'aux heat' I see 'emergency heat' or 'backup heat' so I can only assume all three terms refer to the same spec.

House is in CA, USA.
How can I tell if the heat pump has aux heat?