SpeciesID ParentSpeciesID TimeOfFirstOccurrence InitialReadingFrame Genome
where ParentSpeciesID is the ID of the species from which the present species is descended; TimeOfFirstOccurrence is the time slice in which the first organism of the species was born; InitialReadingFrame is the frame in which the genome of the first organism of the species is being translated, expressed as a number in the range 0-5 (because codons are 6 bits long) indicating an offset from the beginning of the genome; and Genome is a full listing of the species' genome (written as a bit string).
When a species which has been recorded in species_current.dat becomes extinct, the record of that species is removed from this file, and transferred to species_extinct.dat. When this happens, two extra fields of information are appended to the line describing the species: TimeOfExtinction and FinalReadingFrame (the reading frame in which the last organism of the species was being translated).