Critically representative features for use in mask-making verification andor resist development verification are defined andor copied into the in-scribe area used by wafer CD features. The retaining device further comprises a plurality of clipping portions, said clipping portions forming a retaining space for receiving the soldering ball jointly, and at least one of said clipping portions defining a guiding surface and a recess. For instance, the acknowledge waveform required to respond to a received WLAN packet is pre-computed and stored in the PC memory. GPS position data and historical GPS position data can be exchanged between cell phones of buddies and instant buddies such as tow truck drivers via a buddy watch server. Methods for preventing de novo development of cancer are also disclosed. The file management method includes: photographing an image in a photographing mode, playing back stored image files in a playback mode, selecting an image file to be deleted according to a manipulation by a user in the playback mode, and deleting the image file from a storage medium after the playback mode is changed to the photographing mode.