John van der Berg V reads family van der Berg V — the particle chain and the maiden walk take a trailing numeral as a name word #424

Two other sites stop at a suffix with the same test #401 corrected for the bound-given reserve, and both swallow a bare trailing roman numeral:

John van der Berg Jr     ->  family='van der Berg'    suffix='Jr'
John van der Berg V      ->  family='van der Berg V'  suffix=''      chain took the numeral
John van der Berg X      ->  family='van der Berg X'
abdul van der Berg V     ->  family='van der Berg V'

John née Jones Smith Jr  ->  maiden='Jones Smith'     suffix='Jr'
John née Jones Smith V   ->  maiden='Jones Smith V'   suffix=''      walk took the numeral
Jane Smith née Jones V   ->  maiden='Jones V'

Compare John Smith V → family Smith, suffix V.

Why

P2's chain runs "until … a trailing suffix begins", and M2's walk takes the words after the marker "up to any trailing suffix". Both test that boundary with _is_suffix_piece, which vetoes on the initial tag — right for assign's middle-initial question, wrong here for the reason #401 recorded: a bare V is suffix vocabulary and initial-shaped, so neither site sees the suffix assign will then read. Once the chain or the walk has taken the numeral into its piece, assign never sees a lone trailing V at all.

Scope

Pre-existing, independent of #423 (measured at 2.2.0dev). Single-letter numerals only — V, I, X — after a particle chain or a maiden marker; II, Jr, PhD are unaffected. No differential corpus name has either shape; tests are the verification.

Fix

_vocab.is_trailing_numeral_suffix (shared by assign and the bound-given reserve since #423) answers the question both sites ask; each stop needs the same "last piece of the walk, preceded by a non-initial-shaped piece" framing the reserve uses. Worth doing as one change with one set of examples, since it is one predicate at three sites — and the same altitude question as the acronym follow-up: if assign's suffix verdicts were computed once and shared, none of the three sites would carry its own copy.