Standards
Citations and sources
How cited references are checked, and what that check can and cannot establish.
What is checked
Cited references are checked against Crossref. A reference that does not resolve is reported to the author, with the reference named. The check samples the reference list rather than reading every entry. Crossref matches by title, so a close match is possible.
Coverage is not complete. Crossref does not hold every record, and preprints in particular may not resolve. An unresolved reference is reported to the author as unresolved, and is not treated as evidence that the source does not exist.
What a resolved reference means
A resolved reference is a reference that exists. It is not a guarantee that the source is used correctly, or that it says what the citing sentence claims. That judgement belongs to the reviewer.
On the article page
Each check that ran on a paper appears as one row, naming the tool that ran it.