This International Standard establishes a laboratory test method and performance requirements for operator protective structures (OPS) on forestry machines. It is applicable to mobile forestry machines as defined in ISO 6814 engaged in felling, processing, forwarding and skidding. The OPS are designed to provide reasonable protection from penetrating objects such as saplings, branches, broken winch lines and poking hazards in forestry work, but not from small, thrown objects such as chain teeth. Those OPS meeting the performance criteria will not provide complete operator protection under all conceivable circumstances, but are expected to minimize the possibility of operator injury in normal operational situations.