The width, in pixels, of the smallest byte-addressable group of pixels (type CFNumber). Used to assist with allocating memory for pixel formats that don’t have an integer value for bytes per pixel. Assumed to be 1 if this key is not present. Here are some examples of block widths for standard pixel formats:
Available in Mac OS X v10.4 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)