This function reads data files in the PC-Axis format.
The format is described in the two documents in the reference section.
According to them, null values can be encoded using ".", "..", "...", or "....".
Also, the documentation is not very specific concerning the actual encoding to be expected in
PC-Axis files.
It is however quite safe to assume that they will be encoded using some "latin1" variant.
The alternative value for the encoding
argument would be "utf-8".