Qualification policy

Qualification follows this authority order:

  1. accepted qualification evidence for already-closed behavior;

  2. canonical XSTAR Fortran 2.59g executable semantics;

  3. papers/manuals for explanation and scientific context.

The parity boundary is machine-readable in qualification/parity_freeze.json and enforced by tools/qualification/check_parity_freeze.py.

Normal productization changes should run the relevant targeted characterization gates. Scientific/orchestration changes use representative fast fixtures first. All-62 qualification is reserved for deliberate science changes, release candidates when required, or explicit parity campaigns rather than every documentation/API change.

Material numerical science, inventory/membership, rank/order, and attachment diagnostics remain distinct surfaces. Known structural exceptions belong in qualification metadata rather than being hidden by broad tolerances.

Cross-platform portability qualification

The accepted 0.6.88.6.1.2.1 portability contract distinguishes same-host reproducibility from cross-platform numerical equivalence. A fixed-state run is repeated on each host and must be raw-byte deterministic against itself. Cross-host comparison then requires exact discrete state and FITS structure, normalizes text line endings, and applies the strict dual limit of relative difference <= 1e-13 and ULP distance <= 64 only to differing finite floating values.

This avoids treating CRLF serialization or legitimate last-bit architecture differences as scientific regressions while retaining exact checks for traversal/inventory/order/schema and strong per-host determinism. See Cross-platform portability status.