U.S. stocks opened flat on Tuesday as investors took another pause after last week's big rally, with the Fed expected to raise interest rates a quarter point on Wednesday. The Dow Jones industrial average <.DJI> was up 0.51 points, or 0.00 percent, at 10,391.82. The Standard & Poor's 500 Index <.SPX> was down 0.05 points, or 0.00 percent, at 1,164.84. The technology-laced Nasdaq Composite Index <.IXIC> was down 0.05 points, or 0.00 percent, at 2,039.20.///