title: Plotting multiple time series in BIRT
body: <p>As a new Birt user I am now facing the challenge: I have a set of temperature measurements T1 T2 T3 and T4. The data is like <em>T1: [(datetime1, temperature1), (datetime2, temperature2), ...], T2: ...</em> and so on. I want to have x-axis as time and y-axis as degrees, and plot 4 curves corresponding temperature measurements.</p>
  
  <p>The questions are
  1. Is it possible to combine all datetimes of the four data sets into a single x-axis?
  2. Is Birt capable of drawing such curves, if there are thousands of temperature samples to be squeezed into?</p>
  
  <p>Thanks for your helpful answers.</p>