Components in a plurality of administrative domains that are communicatively coupled by a network are automatically managed. The apparatus further includes a radiation sensor which is located so as to be able to receive radiation out of the projection beam, said sensor comprising a radiation-sensitive material which converts incident radiation of wavelength 1 into secondary radiation; and sensing means capable of detecting said secondary radiation emerging from said layer. Similarly, each computer has, for each item that it stores, a node of a virtual network for item look-up, with linking data comprising addresses of other such nodes associated with items assigned to the same virtual directory, so that these linking data together define a plurality of virtual networks for item look-up, each of which networks corresponds to a respective different virtual directory. In one embodiment, a plurality of actuations of a hand lever operates a hydraulic pump that moves a locking bolt from a first position in which a locking bolt is engaged with a recess in the fixed structure to a second position in which the locking bolt is disengaged from the recess to permit opening of the gate. The continuous concentric ridge further has reduced reflectance ridge-surfaces facing a top direction away from the focal point of the Fresnel mirror. Variables are named with prefixes to identify data that must be transformed before disclosure.