A 32 bit field that contains: the exponent (8 bits), the length (4 bits), whether this instance is negative (1 bit), whether this instance is compact (1 bit) and 18 bits reserved for future use.
Declaration Syntax Version Information- Available in Monobjc Bridge: 10.6 (For Mac OS X 10.6 and later), 10.5 (For Mac OS X 10.5 and later)