NSNumber containing integer
Default 0, no underline. See “Underlining Patterns”, “Underlining Styles”, and “Underline Masks” for mask values.
Available in Mac OS X v10.0 and later.
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)