parse and validate a genealogy file against the gedcom 7 specification

Steps

1. Fetch the canonical spec from gedcom.io/specs (FamilySearch GEDCOM Version 7.0, PDF and HTML) and the public github.com/familysearch/GEDCOM repository
2. Confirm the file declares compliance via a GEDC structure in the header (GEDC.VERS 7.0) before treating it as GEDCOM 7 rather than 5.5/5.5.1
3. If the header contains a SCHMA substructure, read its TAG definitions first — each documented extension tag's meaning is defined by its URI, not its literal tag, so unknown tags must resolve via that schema
4. Validate structure/cardinality using the repo's machine-readable artifacts: grammar.abnf (line/datatype grammar), grammar.gedstruct (structure organization), and the cardinalities.tsv / enumerations.tsv / payloads.tsv tables
5. Run the file through a reference validator such as the GEDCOM 7 Validator (gedcom7code/js-gedcom on GitHub) which parses, type-checks, and validates GEDCOM generally and v7 specifically
6. Check gedcom.io/changelog for spec revisions between point releases before assuming a given tag/cardinality rule is current