A bib system includes a liquid resistant flexible body member having a bottom configured to cover a torso of a user extending a lower periphery. The second semiconductor layer is formed on the first semiconductor layer and has an oxidation rate which is lower than that of the first semiconductor layer. The robot further includes a tool coupled to the body and configured to hold a structural maintenance tool. A person seeking address information for the address owner may obtain that information by entering an identifier correlating to the address owner, the dates of interest, and if required, a key, into a query in the directory, thereby obtaining accurate address information for the date of interest. The calibration of the probe is analogous to calibration of laboratory spectrophotometers and can therefore be validated. Specifically, the front and rear attachment portions have front and rear offset coupling surfaces engageable with the front and rear engagement surfaces.