1.4 Relationship to Protocols and Other Structures

LZXD (D for Delta) is an LZX variant that is modified to facilitate efficient delta compression.

LZX is a compressor that is based on the Lempel-Ziv 1977 (LZ77) sliding window data compression algorithm, as described in [UASDC], that uses static Huffman encoding and a sliding window of selectable size. Data symbols are encoded either as an uncompressed symbol or as a logical (offset, length) pair indicating that length symbols shall be copied from a displacement of offset symbols from the current position in the output stream. The value of the offset is constrained to be less than the current position in the output stream, up to the size of the sliding window.

The LZXD compression format is used by [MS-OXOAB] to compress data in the offline address book (OAB).

For conceptual background information and overviews of the relationships and interactions between this and other protocols, see [MS-OXPROTO].