Complex sentence: The term is commonly used to denote passenger trainsets that consist of more than one carriage, but single self-propelling carriages, or railcars, can be referred to as multiple units if capable of operating with other units.
Split into simpler sentences: The term is commonly used to denote passenger trainsets consisting of more than one carriage. Single self-propelling carriages (also called railcars, rail motor coaches or railbuses) can be referred to as multiple units if capable of operating with other units.