Example "R__.bot" file showing the Hydrolight standard format for
user-specified bottom irradiance reflectance data.  The default
directory for such files is ..\data\botmrefl.
Ten ascii header records (for identification of the user's data) are expected.
Record 11 begins with (free format) pairs of wavelength (in nm) and 
irradiance reflectance R = Eu/Ed (nondimensional) values.
The last value is flagged by either an end of file or by negative wavelength and R values.
This example file has only four wavelengths.
wavelength   R
   (nm)   (nondimensional)
   350.0   0.037
   355.0   0.042
   360.0   0.045
   365.0   0.050
    -1.0    -1.0