link-sentinels

Date: 2026-09-10. Status: implemented.

Decision. NO LINKP and NO LINK in the large-user linked-postcode field are kept as text and both classified as no link. Ingestion attaches SIMD through each record's own data zone, not through this field. Default SSPL SQL preserves those values with address warnings; only legacy SPD SQL follows links. See sspl-direct-sql-both-publishers.

Reason. NO LINKP is documented for PO boxes. NO LINK is undocumented and appears on six deleted records.

Evidence. 31,725 NO LINKP, 6 NO LINK, 19,273 real links, all resolving.