A more thorough explanation:

Ancipitis usus is a Latin term that refers to conditional contraband. This means goods that can be used for both peaceful and warlike purposes, such as coal and food.

Contraband refers to illegal or prohibited trade, including goods that are unlawful to import, export, or possess. There are two types of contraband:

• Absolute contraband: Goods used primarily for war, such as arms and ammunition, as well as clothing and equipment of a military character.
• Conditional contraband: Goods that can be used for both peaceful and warlike purposes, such as coal and food. This is also known as ancipitis usus.

For example, during times of war, a country may restrict the import of certain goods that could be used to support the enemy's military efforts. Coal and food are examples of conditional contraband because they can be used to power factories and feed civilians, but they can also be used to support military operations.

Overall, ancipitis usus refers to goods that have a dual purpose and could potentially be used for military purposes, making them subject to restrictions during times of war or conflict.