Make an identifier need a dot, an underscore or a digit

[tamnd]

is_version_marker matched any single token of identifier characters, and a single English word is a single token of identifier characters. So Footnotes was an identifier. So were Availability, Examples, Meaning, Exceptions, Author and 1 335 other ordinary words: 9 366 entries over the corpus, every one of them a heading or a table cell that wants translating.

What it cost

The first paragraph of classify.py says a false positive here leaves an English sentence sitting in the corpus wearing a translation's clothes. That is not a hypothetical any more, and this rule is what produced it. 2 808 of those entries were copied through from the msgid and stamped passthrough=version_marker, which is a claim that the string needs no translation.

Written back as English	Entries
Availability	62
Exceptions	25
Author	21
Introduction	18
Description	15
Notes	11

English headings written into a Vietnamese catalog and certified by the tool that wrote them.

The other 6 558 already had a person's translation, and those were hidden a different way. A non-translatable kind is excluded from Corpus.prose(), so no check that reads a translation was looking at any of them. 41 of the words are rendered more than one way across 988 entries, and the disagreements are not stylistic.

Word	Renderings
os	hệ điều hành in all 28, which is the operating system rather than the module
sys	hệ thống in 38, sys in 20
object	sự vật in 50 and vật thể in 23, both a physical thing rather than the computing sense
string	chuỗi in 34, sợi dây in 8, which is a length of rope
statement	tuyên bố in 19, which is a public declaration, câu lệnh in 9
file	tập tin in 18, tệp tin in 12, tài liệu in 6

Why narrowing it is safe

The protection that first paragraph describes was never this function's doing. :mod:`asyncio` and ``sys`` reach is_noop, because stripping the markup leaves nothing behind. This function only ever sees a word with no markup on it, and for those the safe direction is the one the module already states: a wasted call costs a call, and an English heading in a Vietnamese page is not noticed until a reader meets it. There is a test for that now, so the reasoning is checked rather than asserted in a comment.

The rule

A dot, an underscore or a digit somewhere in it. That keeps os.path, __init__, size_t, PyMem_RawMalloc and 3.14, and lets go of every bare word. The dotted form is written segment by segment rather than as one character class so that a trailing dot does not count, because Success. is a one-word sentence and the old pattern took it.

What it costs

Not free. The 2 808 go back to being untranslated, which is what they are, and a full run grows by 43 batches. In the content repo this turns 2 826 passthrough entries back into empty ones and apply --check reports 311 files, so the corpus needs re-applying and those headings need a real translation before that gate is green again.

Corpus counts re-measured: prose 72 496 to 75 660, version_marker 3 843 to 650, noop 5 692 to 5 721. The 29 that went to noop are single letters, which no rule but the word rule ever explained.

Refs #11