Abstract: A portable linear fastener driving tool is provided that drive staples, nails, or other linearly driven fasteners. The tool uses a gas spring principle, in which a cylinder filled with compressed gas is used to quickly force a piston through a driving stroke movement, while a driver also drives a fastener into a workpiece. The piston/driver is then moved back to its starting position by use of a rotary-to-linear lifter, and the piston again compresses the gas above the piston, thereby preparing the tool for another driving stroke. The driver has protrusions along its edges that contact the lifter, which lifts the driver during a return stroke. A pivotable latch is controlled to move into either an interfering position or a non-interfering position with respect to the driver protrusions, and acts as a safety device, by preventing the driver from making a full driving stroke at an improper time.

Abstract: The present invention provides a system, computer program and method for recognizing users by creating one or more certificates and issuing the one or more certificates to a first user. Each certificate has a certificate identifier and the first user has a first user identifier. The certificate identifier and the first user identifier for each certificate issued to the first user are stored in a database. At least one of the certificates given to a second user having a second user identifier by the first user is redeemed and the second user identifier is stored with the certificate identifier in the database for each certificate given to the second user.