The density of water as a function of temperature.
Sample data file, CurveExpert 1.0

T(F)          rho(kg/m^3)
=============================
32.000000       62.400000       Comments can be interspersed
40.000000       62.400000       throughout the data file, as
50.000000       62.400000       long as they do not come before
60.000000       62.300000       the numbers on the same line.
70.000000       62.300000       Also, there must be two numbers
80.000000       62.200000       per line -- the first number is
90.000000       62.100000       the X data, and the second number
100.000000      62.000000       is the Y data.
150.000000      61.200000
This may be distracting, but CurveExpert can work around
comments and text in the data file.  This means that you
don't have to spend time removing all of the 'garbage' that
might happen to coexist with your data when it is exported
from your software packages.
200.000000      60.100000
250.000000      58.800000
300.000000      57.300000
350.000000      55.600000
400.000000      53.600000
450.000000      51.600000
500.000000      49.000000
550.000000      45.900000
600.000000      42.400000
This is the end of the data.  Comments may be put here also, 
with no harm.