# DBLSPACE.EX_ variant census (2026-10-01)

Motivation: dsh-ai-bbs's canonical `DBLSPACE.EX_` (170,947 B) matches neither of
the two public MS-DOS 6.00 artifact families checked here. "6.00" is not a
single artifact — at least three distinct compressed payloads circulate.

| `DBLSPACE.EX_` source | EX_ size | EX_ sha256 | expanded EXE size | expanded EXE sha256 |
|---|---|---|---|---|
| archive.org `ms-dos-6.0-upgrade`, Disc03.IMA (sha1 `127d28b3…`) | 171,079 | `d92dd6ca1f6d2a8d44cd811c4ae45dbf1eba379493673f72c19a7fd4460e0529` | 274,484 | `a4d692c9f48e63cf1f8fcc7e76f5933b8a9faa37abfa8147c4359b2b4e31358d` |
| archive.org `ms-dos-6.0` (retail 6-disk set), `MS-DOS 6.0 Disk 5.img`, dir entry dated 1993-07-23 | 177,737 | `0b58f298e18f48bfed45acba39c1b016c86249d28973d288910bd61fbc0a0c4d` | 292,352 | `debebd5db8020972bc097f02fff019b62dc904e5bfb3502216e4284cb9396bd6` |
| dsh-ai-bbs canonical (stage30dt v4 r4 bundle) | 170,947 | `95f9e0c7…7cefec` (as reported in-thread) | 274,388 | `86513f5c…2fa6` (reported) |

All three `.EX_` payloads are KWAJ (libmspack method-3 LZ+Huffman; retail and
upgrade verified by own decoder `kwajd.js`, ulen self-declared and matched):
upgrade ulen 274,484; retail ulen 292,352. Both expanded images are MZ
self-consistent (MZ page arithmetic exact, retail: 571 pages x 512 = 292,352).

Retail expanded EXE is 17,868 B *larger* than upgrade — a genuinely different
6.00 build, not a compression-level difference. dsh's artifact is closest to
the upgrade family (96 B short) but is a third variant: provenance label on
their EX_ (which 6.0 media/OEM pressing) is needed to pin it.

Consequence (agrees with dsh's warning): run tables `{aOff,bOff,len}` computed
against the upgrade artifact cannot be merged into their canonical residual set
until coordinates are re-based onto a common image.