A magnetic head slider for eliminating the fluctuations of contact forces between a magnetic head and a recording disk due to changes in atmospheric pressure or shocks includes a plurality of fluid force generating faces positioned at a plurality of different height levels. A tile of the detection target light path is detected from the light receiving positions detected respectively. A call center may send a query requesting language preference information of the user to the calling apparatus when the user makes a call connection to the call center. The arcs of the torches form a weld in the groove.