This track displays the operon predictions done at The Institute for Genomic
Research (TIGR). The method of prediction is described at this URL:
http://www.tigr.org/tigr-scripts/operons/operons.cgi
Basically, it's an approach that tries to find "conserved gene
pairs", i.e. the gene sequence is conserved, and near the other gene on the same
strand in more than one genome. This might not be the best method for archaeal
genomes so many of the ORFs are annotated as hypothetical. In Pyrobaculum aerophilum
for example, out of 2605 total genes, only 501 are predicted to be a part of one of the
174 operons.