An evacuation list is the roll call a fire warden works from at the assembly point. It combines employees who have checked in with visitors and contractors currently signed in, so the count reflects who is actually in the building rather than who was rostered.
This is the reason most organisations replace a paper visitor book. A book left burning at reception is no use outside. A visitor management system puts the same list on a phone, updated as people check in and out.
Test it before you need it. A list that takes three taps to reach in a calm office takes far longer in a real evacuation.