Sample corpus: DESCRIPTION-FILE:DESC and :LINK from 13 vendor floppies

These are the real files the DESC and :LINK findings were checked against, kept here so the evidence outlives the disk images and the session that extracted them. Nothing in DESCRIPTION-FILE-FORMAT.md or LINK-FILE-FORMAT.md has to be taken on trust - re-run the checks against these.

Provenance. Extracted 2026-08-17 from SINTRAN floppy disk images with ndtool -x -F 'FLOPPY-USER/*' -o <dir> <image>.img. Every directory below is named after the image it came from. The DESC file is DESCRIPTION-FILE.DESC in each; :LINK files are stored alongside it, named after their segment. :PSEG and :DSEG files are not copied here - they run to megabytes and only their sizes matter, which are recorded below.

Twelve distinct products across seven years, from unrelated release lines.

Directory	Floppy directory	Domain name in DESC	Segment	.pseg	.dseg	:LINK bytes
ND-disk-00458	ND-10190D-PART1	FORTRAN-500-D	FORTRAN-500	152832	477085	12545
8_nd_f0b_10177h00-1s_fe	10177H00-1S	COBOL-500-H00	COBOL-500-H00	172735	343997	11361
ND-disk-00042	210319H02	LINKAGE-LOAD-H02	LINKAGE-LOAD-H02	123989	2184977	0
ND-disk-00096	211159A01-XX-01D	LED-FORTRAN-A01	LED-FORTRAN-A01	267382	1017597	13057
ND-disk-00093	210190K02-XX-01D	FORTRAN-500-K02	FORTRAN-500-K02	309413	548865	18561
ND-disk-00092	210177K01-XX-01D	COBOL-85-K01	COBOL-85-K01	265213	129253	17089
ND-disk-00095	211160B03-XX-01D	LED-B03	LED-B03	223695	394525	0
ND-disk-00172	210814L05-XX-01D	HYPHEN-TEST-L03	HYPHEN-TEST-L03	153595	454545	28737
ND-disk-00177	210874L05-XX-02D	SL202-FO-L27	SL202-FO-L27	252164	288783	344641
ND-disk-00022	211078A01-EN-02D	OEM-STATU-A01	OEM-STATU-A01	191144	677897	30337
ND-disk-00215	211066D10-SW-02D	RG-SERVICE-D	RG-SERVICE-D10	120342	77825	24353
ND-disk-00216	210528D10-SW-01D	NOTIS-RG-SW-D	NOTIS-RG-SW-D10	442113	247809	43937
ND-disk-00217	210528D10-SW-02D	RG-START-SW-D	RG-START-SW-D10	231578	114689	30209

Every floppy also carries a SCRATCH-DOMAIN / SCRATCH-SEG-01 pair, whose .pseg is 5 bytes and .dseg 1029 bytes everywhere except the 1982 floppy, where both are 5.

Things this table already shows

• The domain name and the segment file name are not the same string. RG-SERVICE-D is the domain; RG-SERVICE-D10 is the segment. Anyone matching one against the other will get nothing. LINKAGE-LOAD-H02 is exactly 16 characters and therefore has no 0x27 terminator, which is why the terminator convention went unnoticed for so long.
• :LINK is optional. The linker and the symbolic debugger both ship without one.
• DESC is 22528 bytes in all thirteen, with domain entries at bytes 256 and 312 and segment chains at 0x4000 and 0x40C0, across seven years. The layout did not drift.

Reproducing the checks

Size rule, PLB + PSIZE + 1 = .pseg and DLB + DSIZE + 1 = .dseg - 48 comparisons, no mismatches:

nd500-dump <dir>/DESCRIPTION-FILE.DESC

and compare against the .pseg/.dseg columns above. nd500-dump is built from the pcc-nd500 repository, src/nd500-dump/.

Take segment file sizes from the image directory (ndtool -t <image>.img), not from extracted copies. A file with a non-zero byte count but zero allocated pages extracts as empty. That happens on the 1982 floppy and it looks exactly like a format anomaly. It is not one.

The browser viewer in ../viewer/ parses these same files and is kept in agreement with nd500-dump - both read domain entries by index at 56*index + 256*(index div 32 + 1) and follow the segment chain.

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See: ../DESCRIPTION-FILE-FORMAT.md, ../LINK-FILE-FORMAT.md