Without knowing what species you are asking about, the answer here will be specific to elk only.
If you purchase an OTC elk tag for the Middle Fork Zone, which includes unit 27, you may hunt any unit in that zone (20A, 26 or 27). Those are the only units that you may hunt with a Middle Fork Zone elk tag. Season dates, weapon restrictions and other special rules all apply. See our big game proclamations for more details. The 2014 big game proclamations should be available the end of April 2014.
If this is not the species you are asking about, please submit another question with information about the species you are interested in hunting.