I would suspect that "unintentional fall" also covers falling over (like, the kind of fall that would happen if you tripped over a garden hose), not just falling off something. The former is the most common cause of emergency visits among the older people I know.
I figured for all ages it would also encompass falling off something. A chair, bed, etc… one type is more predominant for the younger ages (falling from something), the other is likely more predominant for the older ages (falling down, tripping, stairs, etc).
Falls hit 50% fatal above a twelve foot drop. Remember kids gravity is an accelerative force. It isn't a static force. You fall faster and faster every second you fall.
