System and method for designing, developing and implementing Internet Service Provider architectures. Therefore, an output having a resolution two times higher than that of the movable object having a phase difference of 90\xb0 can be obtained, where the width of each of light receiving elements 22a-22d is P. A plurality of tumblers actuable by the key and an additional blocking element movably arranged in a guide passage of the cylinder core project into the keyway, said additional blocking element being displaceable obliquely or transversely to the direction of insertion of the key. The system also has a package distribution module which allows users to send the package content files to one or more users using a variety of transferring techniques. The backup system then utilizes hypervisor snapshot capabilities of the host server to record intended changes to the virtual machine disk files while such files are being copied by the host server. The first hole reaches the foundation layer without contacting any other first holes.