Article 188

A person who is lawfully in custody and who together with others engages in conduct which causes or creates a risk of causing damage to property or physical injury to a person with intent to escape, to coerce another to perform or restrain from performing an official duty, or to attack such person,

is guilty of riot in a prison, a Class 9 serious offence, punishable with a definite term of imprisonment of not less than 1 year and not more than 3 years.