No mode returned for Perkin Elmer PEPE format

[davidbenncsiro]

See https://github.com/csiro/soilspec.format/blob/main/R/perkin_elmer_format.R#L182

[davidbenncsiro]

Via a hex viewer we see evidence of strings like "Absorbance" in our example.sp file.

What is really required in order to make sense of this is a file format specification.