Trust
How is roll call taken during an evacuation or a drill?
The moment an incident opens the roster is frozen, people are marked safe or missing, and for a missing person the last gate and time is a required field.
Detail
The frozen roster and subsequent movement are kept apart; merging them loses track of who is where.
A drill runs through the same flow and its duration is measured with an evidence record.
Source
Source: the product's emergency flow.