A long value which represents the CCITTK. The values are -1 for Group 4, 0 for Group 3, and > 0 for Group 3-2D, where this value is the size of the encoded group.
Remarks
It is the same as the K entry of a CCITTFaxDecode filter. For more information see PDF Reference 1.7 at www.adobe.com/devnet/pdf/pdf_reference.html, section 3.3.5, table 3.9.