A cataloguing block states subjects in Library of Congress form, which
is precise, deep and no use for browsing. Real blocks from this library
read 'Political science – Early works to 1800' and 'English
literature—Middle English, 1100–1500—History and criticism'. Nobody has
a shelf called that.
--shelf takes the closed list the library is actually browsed by and
files the printed headings onto it, longest term first so a period of
thought does not collapse into its parent. Matching is on whole words
after folding punctuation away, because a cataloguing block separates
with em dashes, en dashes, full stops and plain hyphens, often three in
one heading, and OCR turns any of those into any other.
What matches nothing comes back under unshelved rather than being
dropped: a subject silently discarded is indistinguishable from a book
that printed none, and the difference is the whole value of reading the
block.
An ISBN is not a DOI. The body that assigns a DOI is the only one that has
it, so one register is the whole answer. A book's identifier is assigned by
its publisher and recorded by whoever gets round to it, and the record that
comes back is as often as not missing the thing the caller wanted: asked
about 9780199205592, OpenLibrary's edition record names *The First World
War* and the press that printed it, and nobody at all as its author, because
an edition record names its authors by key.
So an ISBN now has a chain rather than a register. The edition record first,
then OpenLibrary's own index — which answers with `author_name` filled in
and costs nothing — and Google Books last, because it answers anonymous
callers only until a daily quota runs out, after which it replies 429 to
everyone behind the same address, as it is doing here today.
The first complete answer wins, an incomplete one is kept in case nothing
better comes, and a register being down is a failure only when every
register is. `source` on the record says which one answered.
colophon comes with it: the imprint reader was taking `Oxford is a
registered trade mark of Oxford University Press` for a publisher and
`Oxford N`, off `Oxford New York`, for a place. A legal notice mentioning a
press is not the press, and a city is the city and not the first letter of
the next one.
A catalogue's worst records are the ones whose file says nothing true about
itself: a PDF titled `Untitled` by an author called `Oxford`, which is a
publisher, from a filename that was never anything but a filename. What
those books do have is pages. The title page carries the title as the
publisher set it; the copyright page carries the imprint, the year, the
ISBN, and in most English books since the 1970s the cataloguing block, which
is a catalogue record a librarian already made, subject headings and all.
So this reads the pages. Every field names the page it came from, and a book
that printed nothing comes back empty with its fields in `unsettled` rather
than filled with something plausible — an extraction that starts at chapter
one has no front matter in it, and saying so is the answer.
Two pages look like a title page and are not, and both are how a catalogue
comes to name the wrong book. A series advertisement lists other titles in
the shape a title page uses, over as many as four pages with only the first
announcing itself. A translation's cataloguing block prints the original
title in brackets above the real one. Both are found and refused.
Three things the pages give that no file does: the subject headings a
librarian assigned, an ISBN that exists only in print — which turns a book
with no identifier into one `bibfetch` can look up — and a title in the case
the publisher meant, because a half title prints unbroken what the title
page breaks across two lines and sets in capitals.
`--prompt` and `--merge` are citefind's: a question about exactly the fields
the pages left unsettled, composed here and answered wherever the caller
keeps a model, with the advertising taken out of what the model is shown.
A field a model answered is marked `model`, so a record always says which of
it was read and which was inferred.
Measured against 600 books of the home corpus: the cataloguing block
answered for 21% of them and agreed with the catalogue 89% of the time, most
of the residue being the catalogue's error rather than this one's. Title
pages answered for another 41%. The remaining 38% print nothing readable,
and are what the prompt is for.
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