Mekkar VII is a Peacekeeper maximum labor planet. The facility there is divided into a number of levels each of which may possibly have a specific purpose. Various species are interned in the facility's many levels.
Both Zotoh Zhaan and Ka D'Argo were imprisoned at Mekkar VII at some point in their sentences. Zhaan spent three cycles there, working with a Peacekeeper intellilan interface. This work would later giver her familiarity with Peacekeeper coding.
During his time there, D'Argo worked on the ninety-third level in the kemlac mines, work and conditions known for their high fatality rate. D'Argo managed to survive as many died around him, later saying that the experience had made him stronger. ("Premiere")