Source hierarchy
Tier A sources are primary documents, official records, direct transcripts, and first-party material. Tier B sources are reputable independent reporting. Lower tiers may guide research but cannot carry a record by themselves.
Policy
Source policy
These operating rules are part of the public product—not an afterthought to the score.
Access and excerpts
We store only what the license and public-interest purpose allow. Public pages show short, relevant excerpts and links back to the original source whenever possible.
Availability
A source becoming unavailable triggers review. The original record remains marked and may be corrected, limited, or retracted if evidence can no longer be supported.
For the full operational policy, see the corresponding repository documentation before enabling a public production environment.