1 Introduction

The Xpress Compression Algorithm has three variants, all designed for speed.

The fastest variant, Plain LZ77, implements the LZ77 algorithm ([UASDC]).

A slower variant, LZ77+Huffman, adds a Huffman encoding pass on the LZ77 data.

A third variant, LZNT1, implements LZ77 without the Huffman encoding pass of the second variant, but with an encoding process less complex than Plain LZ77.

Sections 1.6 and 2 of this specification are normative. All other sections and examples in this specification are informative.