A more thorough explanation:

De onerando pro rata portione is a Latin legal term that means "of charging according to a ratable proportion." It refers to a writ that was used in the past for a joint tenant or cotenant who was being charged more rent than their fair share.

For example, if two people were renting a house together and one of them was being charged more rent than their fair share, they could use the writ of de onerando pro rata portione to challenge the unfair charges. The writ would require the landlord to charge each tenant a proportionate amount of rent based on their share of the property.

Another example would be if a group of farmers were sharing a piece of land and one of them was being charged more for the use of the land than their fair share. They could use the writ of de onerando pro rata portione to ensure that each farmer was charged a proportionate amount based on their use of the land.

These examples illustrate how the writ of de onerando pro rata portione was used to ensure that each person was charged a fair and proportionate amount for their use of a shared property.