S. cerevisiae in snpEff databases

On snpEff 5.0, if you do java -jar snpEff.jar databases and look for Saccharomyces cerevisiae, you will find (among many other entries):

R64-1-1.75                                                      Saccharomyces_cerevisiae                                                                                        https://snpeff.blob.core.windows.net/databases/v5_0/snpEff_v5_0_R64-1-1.75.zip
R64-1-1.99                                                      Saccharomyces_cerevisiae                                                                                        https://snpeff.blob.core.windows.net/databases/v5_0/snpEff_v5_0_R64-1-1.99.zip
Saccharomyces_cerevisiae                                        Saccharomyces_cerevisiae                                                                                        https://snpeff.blob.core.windows.net/databases/v5_0/snpEff_v5_0_Saccharomyces_cerevisiae.zip

The entry that is simply named Saccharomyces_cerevisiae — what is it? Is it a reference database? Possibly the latest R64 which would be R64-3? Or is it something else?