What is a primary source of facts about a structure for firefighting operations?

A preincident plan is a comprehensive document that provides essential information about a structure before an emergency occurs, making it a primary source of facts for firefighting operations. This plan typically includes details such as the building's layout, fire protection systems, occupancy types, potential hazards, and access points. The information gleaned from a preincident plan helps firefighters understand the complexities of the building and devise effective strategies for tackling emergencies, ensuring safety and efficiency during operations.

Other options, while they may contain useful information, do not serve in a primary capacity as effectively as a preincident plan. Fire reports provide insights into past incidents but lack preemptive planning information needed for future emergencies. Building permits contain structural details but do not focus specifically on operational needs related to firefighting. Insurance reports outline risk assessments and coverage details related to the structure but do not provide the immediate operational information required during an incident. Thus, the preincident plan stands out as the most relevant source for preparing firefighting strategies.