Berg, Jan vd reads the Dutch van der abbreviation as a post-nominal decoration #380

vd carries two real readings: the Dutch abbreviation of van der, and the British Volunteer Officers' Decoration. Trailing position always resolves to the decoration:

Berg, Jan vd     given='Jan'   family='Berg'      suffix='vd'
Berg vd          given='Berg'                     suffix='vd'
Jan vd Berg      given='Jan'   family='vd Berg'                  <- leading position is fine

Per #379, Berg, Jan vd should give family='vd Berg' — it is the same Dutch sorted form as Beethoven, Ludwig van. But the decoration reading has to keep working:

John Smith VD         suffix='VD'
Col. John Smith VD    suffix='VD'

The entry is legitimate

vd arrived in 962f235 ("add post-nominals from danhartropp in #7") as part of a UK honours list, alongside RD, VRD, TD and ED — the reserve/volunteer decoration family. #7 was scraping the UK parliament website. This is not a bulk-import artifact like rai in #342, and it should not simply be removed.

Neither existing mechanism arbitrates it

The positional rule described in #289 — an ambiguous acronym is a credential when removing it still leaves a given and a family name — fires correctly by its own logic here, since removing vd leaves Jan + Berg. It has no way to know about the Dutch convention.

The period form does not separate them either: both vd and V.D. are attested spellings, on both sides of the ambiguity.

A signal that might

Dutch tussenvoegsels are lowercase (vd, v.d.) while the decoration is uppercase (VD). That is exactly the letter-case signal #289 proposes, so this may be a case for that mechanism rather than a new one. Note #289's current scope is the four words in suffix_acronyms_ambiguous (do, ed, jd, ma); vd is not among them, so adopting it there would widen that issue.

Not the same as mc

mc looks like the same shape and is not. Moving it to the never-given half per #360 changes no suffix reading — measured:

Mc Donald        shipped: given='Mc' family='Donald'   mc moved: family='Mc Donald'   (the #360 fix)
John Smith MC    shipped: suffix='MC'                  mc moved: suffix='MC'
Donald mc        shipped: suffix='mc'                  mc moved: suffix='mc'

Trailing mc routes on suffix_acronyms membership, which curation does not touch. There is also no naming convention that writes Mc Donald as Donald mc, so the collision is theoretical there and live here.

Related

• Beethoven, Ludwig van puts the tussenvoegsel in middle instead of the family name #379 — the tussenvoegsel comma form, which deferred this case explicitly
• Use letter case to disambiguate suffix vs. surname: "Jack MA" vs "Jack Ma" #289 — letter case as a possible mechanism
• Rai is parsed as a post-nominal suffix, consuming a common South Asian surname #342 — contrast: a genuinely bogus suffix entry
• Mc Donald and Ste Marie read the particle as the given name #360 — the particle curation that raised the question