paper size defined in ISO 216 (648×917 mm) Bills C-1 and S-1, a pro forma bill normally introduced at the start of a parliamentary session in the Canadian House of Commons C1, also known as Vlakplaas, a unit of the South African Police responsible for assassinating opponents of Apartheid during the 1980s C1, a level in the Common European Framework of Reference for Languages C1, the use class for hotels, in town and country planning in the United Kingdom C1, a NRS social grade in the United Kingdom for the lower middle class a 2001 1.3 megapixels Olympus digital camera model a class of FM radio broadcasting in North America C1 pylon, a type of high voltage pylon Caldwell 1 (NGC 188), an open cluster in Cepheus C-1 visa, a type of visa for individuals transiting through the United States See also Cl (disambiguation) CI (disambiguation) 1C (disambiguation)