One source, or one we could not independently confirm — usable, labelled, not trusted.
Compiled means a date rests on a single source, or on sources we could not establish as independent, or was computed from a published rule we have not confirmed against the instrument.
Most of the corpus is compiled, and printing that on every row is the entire point of the ladder. A dataset that grades nothing is claiming uniform confidence it does not have, and the reader finds out where the weak rows are the expensive way.
Compiled is not a warning about the jurisdiction. Bolivia is not less reliable than Belgium; our evidence for Bolivia is thinner, and those are different sentences. It is a statement about our sourcing and nothing else.
Compiled is one source, or several sharing an upstream. Corroborated requires genuine independence.
Compiled describes how well we know it. An exact date can be compiled, and a verified date can be an estimate.
See also assurance · verified · corroborated · precision
We hold this as assurance: compiled — the majority of the corpus. See what we hold.