How to tag opening_hours for regular AND emergency hours

For example, a place is open Monday-Friday 7:30am-5:30pm. Meaning tag is this:

opening_hours=Mo-Fr 07:30-17:30

However business also has 24/7 emergency service by phone number for example.

This could be a doctors office or HVAC repair company for example.

Is there a tag to represent emergency 24/7 service or means to include in opening_hours?

Maybe you can use additional in opening_hours >> Mo 07:30-15:30 || “24/7 emergency service”.
There is also a service_times key in wiki. Not invented for this but maybe usable?

Or even use a separate key as these are effectively separate services, e.g., emergency_opening_hours or emergency:opening_hours. However I suspect the service_hours key may be just as appropriate for the 24/7 service.