Burrows-Wheeler-transform-based compressors rely on local context regularity, but structured text also contains dates, counters, identifiers, coordinates, and other digit runs whose values vary differently from their surrounding tokens. STC is a practical BWT-family compressor that separates this source of variation before the component BWT stage. It replaces digit runs in the main stream with an unambiguous placeholder and stores the removed digits in length- and context-conditioned side streams. The side streams use stable bucket ordering and compact digit packing, so the decoder can reconstruct the original run order from the normalized main stream without storing a separate permutation. The resulting components are encoded by a fixed internal BWT/M03-style component coder. On enwik9, STC produces a 157,388,188-byte archive with a 183,174-byte decoder source package, giving a local LTCB-style total of 157,571,362 bytes. A full-enwik9 same-coder ablation shows that the digit-context decomposition reduces the archive by 2,629,561 bytes relative to the no-split control. The result is locally verified by full decode and SHA-256 matching; official benchmark status requires independent maintainer-side verification.

翻译：基于Burrows-Wheeler变换的压缩器依赖局部上下文规律性，但结构化文本中常包含日期、计数器、标识符、坐标及其他数字序列，其数值变化模式与周围标记不同。STC是一种实用的BWT族压缩器，在组件BWT阶段之前分离此类变化源。它将主流中的数字序列替换为无歧义的占位符，并将移除的数字存储于长度与上下文条件编码的侧流中。侧流采用稳定的桶序排列与紧凑的数字打包机制，解码器可由此从归一化主流中重建原始序列顺序，无需存储独立置换。最终组件由固定的内部BWT/M03风格组件编码器进行编码。在enwik9上，STC生成157,388,188字节的压缩档案与183,174字节的解码器源码包，本地LTCB风格总大小为157,571,362字节。全enwik9同编码器消融实验表明，相较于无分离对照组，数字上下文分解使压缩档案减少2,629,561字节。该结果经完整解码及SHA-256匹配本地验证；官方基准状态需由独立维护方进行验证。