1997-98 by
Some Genbank flat files contain only CDSs (e.g. bacteria), some also contain mRNAs (e.g. A.thaliana). When mRNAs are annotated in Genbank, their coordinates are stored and can be used.
The advantage of using mRNA is that, if the mRNA is complete (which is not always the case), the upstream regions aretrieved relative to the transcription initiation site, rather than the start codon.
Remarks