The header's metadata as OWNED JS values, copied out of the FlatBuffers table: CityJSON version, transform, geographical extent, the attribute column schema, and which columns carry a B+tree index.
Where each section physically starts and how long it is -- the R-tree, the attribute indices, and the feature section. Derived arithmetically from the header, then validated against the resource's real byte length, so a truncated file is rejected at open rather than mid-scan.
The generated FlatBuffers accessor, for callers that need a field this port's FileInfo does not surface (e.g. the point-of-contact fields).
Everything the reader learned from the file's header, and the only part of an
.fcbfile that is read eagerly. Obtained asreader.header; every query and every CityJSON emission is driven from it.