Copies and surrogates

A book, an article, a manuscript or a find from a trench is a resource: the thing your research is about. What you actually hold of it is a surrogate. That might be a scanned PDF, an afternoon’s photographs in a reading room, a library’s IIIF digitisation, or a film of an object turning on a stand. Pangur keeps the two apart, so a file records what it stands for as well as what it is.

Surrogates come in copies, one for each campaign of imaging or set of files. A copy is what Pangur’s model calls a surrogate set, and the assistants’ tools and the API use that name. This page uses both.

Resources and their parts

Every item in your library is a resource. So is a manuscript in the catalogue that has no library record yet.

A resource can have parts. For a manuscript these are its folios, which you arrange in the catalogue: reorder them, insert blanks and group two photographs into one leaf there, and every surrogate of that manuscript follows. A book’s parts are pages, and an object’s are its sides or faces. Give any other resource its parts with Add parts…, in a copy’s More → Manage pages and parts… on Read: choose pages, leaves, sides or faces and how many, and Pangur numbers them (“p. 1”, “f. 1”). You can also write their names one per line (“Obverse”, “Reverse”). New parts follow any the resource already has. Until a resource has parts, its surrogates stand for the whole of it.

Copies (surrogate sets)

The photographs from one visit to the archive make a copy. So does the repository’s own digitisation of 2020, or a scan made from microfilm. Each copy records:

• When it was made (a date or a range), by whom, and who holds the originals.
• How it was made: its method, such as colour photography, microfilm, raking light, multispectral or RTI.
• Why it was made: its purpose, such as regular page photography, watermarks, marginalia, binding, or damage and repair.
• How it stands to an earlier copy of the same resource.

That last field decides which images are current. A copy that corrects an earlier one replaces that copy’s images of every part it covers: the retake of f. 3 that is in focus takes the place of the one that was not. A copy that supplements an earlier one adds another view and replaces nothing. The ultraviolet photographs of a palimpsest supplement the ordinary page photography. A copy can also stand alone.

Files you had before copies existed are gathered into copies the first time you open the item. Photographs are split wherever shooting paused for more than twelve hours, so each visit becomes its own copy. Stored files are grouped by kind, and a linked IIIF manifest becomes a copy of its canvases.

What each surrogate shows

A surrogate can say which part it depicts and in what role: recto, verso, detail, raking light, watermark, colour target. A photograph placed on a folio in the catalogue depicts that folio already. A surrogate can also name a single earlier surrogate that it replaces, for one retake inside a copy that otherwise supplements.

Superseded surrogates are kept and marked Replaced, so the earlier imaging stays on the record.

Looking across copies

On an item’s Read tab, a copy’s More (⋯) → Manage pages and parts… lists its sets, newest first. Across copies narrows to:

• By part: every surrogate of f. 3, from every set.
• By purpose: every watermark set, or all the regular page photography.
• By role: every verso, or every image in transmitted light.
• Current for each part: every part in order, with the surrogate the reader sees for it and the set it comes from (see the reading copy).

In the web client the copies are the strip of cards at the top of Read (Copies in the web client). On iPhone and iPad it is the Surrogates section of the item. A set that holds one file opens that file when you tap it, and its ⓘ shows the set’s details. A set of several opens its grid, and the strip of thumbnails under it opens any one directly. Swipe a set for its details or to delete it.

The reading copy

Each resource has one reading copy, marked with a ribbon on its card. Read opens it. Make reading copy, in the bar under the strip, makes the copy in view the reading copy.

For each part, the surrogate the reader sees is the reading copy’s. A correcting copy’s surrogate takes its place where one replaces it. Where the reading copy has nothing for a part, a supplementing copy’s surrogate fills the gap. Current for each part lists the result.

Until you choose, Pangur picks a stored PDF, then the most recent photographs, then whatever is there.

Transcriptions and leaves stay on their folio

A transcription of a leaf, and a leaf filed in an arrangement, are attached to the folio and photograph they are about. Reorder the folios, insert a blank, send a photograph back to the pool or delete a folio in the catalogue, and each page of transcription moves with its folio. If you group two folios that were both transcribed into one, the fuller transcription stays on the folio and the other is kept aside with the transcription.

Your own vocabulary

Method, purpose, role and relation suggest terms from four vocabularies every project starts with: Imaging method, Imaging purpose, Surrogate role and Surrogate set relation. Each field also takes any word you type. Edit the vocabularies like any other, from Vocabularies…, to hold your field’s own terms. An archaeologist might add orthophoto, section drawing, context sheet and find photograph. A conservator might add infrared reflectography and before treatment. Corrects and supplements are the two relations Pangur acts on. Any other relation is kept and shown on the copy.

Adding a copy

On an item, Add a copy is the last card on Read’s strip. Add to chooses a new copy, named for the day, or one the item already has; More about this copy gives its purpose and method, relates it to an earlier copy, or gives each file a role. Photographs, scans and files share one drop zone, and Or link a library’s digitised copy takes a viewer or IIIF manifest URL. Dropping files on a copy’s card adds them to that copy; dropping them elsewhere on the strip makes a new one. Uploads in the catalogue’s import go to a new copy named for the day in the same way. On iPhone and iPad, the review screen after you photograph or scan asks the same question. The set is made when the upload starts, so this works offline.

Delete this copy…, under a copy’s More, moves its library files to the trash in your library. Photographs stay in the catalogue.

For assistants

Connected assistants use six tools: list_surrogate_sets, create_surrogate_set, add_to_surrogate_set, describe_surrogate, add_resource_parts and set_reading_copy. With these an assistant can find every watermark image of a manuscript, see which surrogate is current for each part, start a set for a new campaign, give a book its pages, record which folio a photograph shows and in what light, or choose the reading copy. In a terminal, zcp copies KEY lists an item’s copies and --reading SET_ID chooses the reading copy.