A zero with a positive or negative sign in EBCDIC is x'C0' and x'D0' which is also the representation for special characters { and }. Using the modified-zoned-decimal these translate to the ASCII values for { and } which is x'7B' and x'7D' and the rightmost nibble is no longer the binary value of the digit.
Chicago Midway International Airport (IATA: MDW, ICAO: KMDW, FAA LID: MDW) is an international airport on the southwest side of Chicago, Illinois, eight miles (13 km) from the Loop. Dominated by low-cost carrier Southwest Airlines, Midway is the Dallas-based carrier's largest focus city, as of 2013.
Midway, which is about 10 miles from downtown Chicago, mainly serves domestic airlines with in-country flights, but also offers flights on Delta. Most flights to Barcelona from Chicago involve a single stop in a major city, such as Madrid, New York, London, Atlanta, or Paris.