A conceptual process, not a claim that every provider uses the same implementation. Open the cases to distinguish missing data, old evidence and a failed recheck.
Authored fictional examples on reserved domains. No provider was contacted and no current link was verified.
Input: Candidate URLs and known references.
Output: A queue of pages to attempt.
What remains uncertain: An undiscovered page can contain a real link.
Input: A queued URL and crawl permissions.
Output: A response, redirect or failed request.
What remains uncertain: A failed fetch does not prove removal.
Input: The accessible representation of a page.
Output: Reported source-target references and attributes.
What remains uncertain: Rendering support and extraction rules differ.
Input: Extracted URLs and repeated observations.
Output: Provider-specific grouping or deduplication.
What remains uncertain: Do not assume providers share a counting unit.
Input: An observation with its timestamp.
Output: Historical records and later observations.
What remains uncertain: The latest successful observation can be old.
Input: Stored records plus scope and filters.
Output: A selected table, sample or downloadable file.
What remains uncertain: The export is not a complete current map of the web.
The hypothetical index has no observation for this source. The real page has not been checked here.
Next check: Investigate discovery and coverage before saying the link is absent.
The example was observed on 10 January and exported on 14 January. No new successful check is recorded.
Next check: Keep the observation date; a fresh export does not prove current presence.
After an earlier observation, the example recheck returns HTTP 503. The response does not establish whether the reference was removed.
Next check: Retry through the normal authorized workflow and keep the prior evidence separately.