The Indonesian Monetary Unit is composed of two parts: the SEN and the RUPIAH. The SEN is a three-letter currency unit, while the RUPIAH is a six-letter currency unit. The SEN is the subunit of the RUPIAH, with 100 SEN equaling one RUPIAH. The RUPIAH is the official currency of Indonesia and has been in use since 1949. It is issued by the Bank of Indonesia and is available in both coins and banknotes.