3.1.8.2 RDP 6.1

 RDP 6.1 supports an extension to the compression techniques described in [MS-RDPBCGR] section 3.1.8. This extension is called "RDP 6.1 Bulk Compression" (RDP6.1-BC) and is supported only for server-to-client traffic. The RDP6.1-BC compressor is unique in that it is a chainable compressor, where the output of the compressor can be passed as input into another compressor to further compress the data stream. This is possible because RDP6.1-BC is a byte-level stream compressor and does not perform bit-level compression. The RDP6.1-BC compressor is referred to as the "level-1" compressor and the chained RDP 5.0 bulk compressor (described in [MS-RDPBCGR] section 3.1.8) is known as the "level-2" compressor.