A screw axis whose row the sweep never recorded - it lies in the spindle's
blind cone, or outside the resolution range - is not a group the data refused,
it is a question nobody asked. The search already offered the whole set in
SPACE_GROUP_ALTERNATIVES, but the per-zone screw table that would say it in
words is printed for the SELECTED candidate only, and the selected candidate
in exactly this case is the one with no screw zones, so the run's account of
the open axis was a blank.
The search now names the axes on which two SELECTED candidates disagree about
whether the row carries screw absences at all, with why the row could not be
judged (never recorded / no control class). The report writes the axes as
SPACE_GROUP_SCREW_UNDETERMINED= beside SPACE_GROUP_ALTERNATIVES and explains
them in prose; the adoption logs a warning naming the axis and the set. An
enantiomorphic or origin-ambiguous pair predicts the same absences on every
row and is not named here - that ambiguity is the hand, or the origin.
Nothing about the decision moves: the group adopted, the alternatives and the
written .mtz/.cif/.hkl are exactly as before, because a reflection file cannot
hold "maybe a screw".
The battery scorer mirrors its existing "hand only" rule: a set differing from
its reference only by a screw the run reports as undeterminable, with the
reference among the groups it offered, scores unscored/screw_undetermined
instead of a sym_screw failure. All three conditions are necessary, so a screw
called wrongly where the row WAS measured stays a failure.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013nW6FNRP1bBJJ8pfHiByAT
leonarski_fandClaude Opus 5
7a6df3c24a