3.1.8.1.2 Compressing Data

Compression using RDP6.0-BC is based on the principles outlined in [MS-RDPBCGR] section 3.1.8.2 with literals and copy-tuples being encoded using the scheme described in section 3.1.8.1.4.3. Also, due to the slide-back behavior outlined in section 3.1.8.1.1, the meaning of the PACKET_AT_FRONT flag (0x40) has changed. This flag MUST still be set in conjunction with the PACKET_COMPRESSED (0x20) flag; however, it is now used to indicate that the history buffer MUST be slid back by half its size and that the HistoryOffset MUST be reset to the middle of the history buffer.