In the Federation standard system of planetary classification, a class H planet was characterized as usually being uninhabitable by Humans. In the Treaty of Armens, "unwanted lifeforms inhabiting H class worlds may be removed at the discretion of the Sheliak Corporate." (TNG: "The Ensigns of Command")
Examples of a Class H planets:
|D • H • J • K • L • M • N • R • T • Y • Other classes|
According to the Star Trek: Star Charts, on page 24, Class H worlds had an age of 4-10 billion years and had a diameter ranging from 8,000 to 15,000 km. They were found throughout a solar system. These desert planets were categorized by a hot and arid surface, with little or no surface water and an atmosphere that might contain heavy gasses and metal vapors. Lifeforms found on Class H planets included drought and radiation-resistant plantlife and similar animal life.