The file singlets.dat can be read with my IDL routine read_struct, or by any
flat ascii table reader.

The top 4 lines form a simple header, that describes the content of the file,
the rest is a flat ascii table corresponding to an array of 6 columns and
5,207,041 lines.

column  1 is nVal     - long   - order,  n
        2    lVal     - long   - degree, l
        3    mVal     - long   - azimuthal degree, m
        4    freq     - double - mode frequency,                                    [uHz] 
        5    sFreq    - double - uncertainty on the mode frequency,                 [uHz] - using the 1% (conservative) systematic contribution
        6    dFreq    - double - ridge to mode frequency correction, zonal value,   (model.freq_ridge - model.freq_mode), [uHz]