Any facts or additional information that you know about the incident. Diagrams may be applicable, if pictures are taken it can be noted here that they will be attached or e-mailed, the weather conditions that existed or conditions of the location (icy/slippery, wet, snow covered), observations about the potential claimant (running, slippery shoes, carrying large box), etc.

Example:

"I did not see the incident, but I spoke with Jane Doe within 1/2 hour of her slipping on the sidewalk. She was wearing no-grip, high-heeled shoes. She told me... Attached you will find the pictures taken..."