Conventions on referencing manuscripts
Lemmata
Every article has a title (the lemma), and in tune with other wikis, the URL is identical with the lemma. In case of manuscripts, the lemma is composed of place name, holding institution, and shelfmark (e.g. Admont, Stiftsbibliothek, Cod. 43). In some cases, the lemma has to be simplified to avoid too long or too complex titles. In particular, the lemma ought always be tripartite with two and only two commas (one after the place name, one before the shelfmark). Also, in the lemma conventional abbreviations like „BAV“ are used. In all these cases, the full details are provided as part of the article.
Consistency in designating manuscripts is generally a good idea, as it helps to find manuscripts, to check arguments, and so on; in the context of a wiki such as the Clavis Wiki, uniform lemmata also help to identify doublets, to spot erroneous shelf-marks, to faciliate searches and mass edits, and to make categories easier to navigate.
The demand for relatively short lemmata derives from the function of these lemmas wirhin this wiki, where they are used in lists and, more commonly, categories effectively serving as indices. The strictly tripartite structure facilitates automatic processing of the short titles.
What is a manuscript, anyhow?
Extant manuscripts
Every manuscript should have one and only one article. Normally, this means that every codex is counted as one manuscript; in all doubtful cases, any fragment, codex, or multi-volume manuscript with its own shelf mark is seen as a distinct object, and hence can have its own article.
From this, it follows that disiecta membra have their individual entries; e.g. St. Paul im Lavanttal, Stiftsbibliothek, 6/1 and Karlsruhe, BLB, Aug. CIII were one manuscript in the Middle Ages but today are kept in two libraries, and hence have separate articles. Vice versa, volumes composed of two or more medieval manuscripts like Arsenal 713 have only one entry. As for multi-volume manuscripts, the Clavis Wiki follows the practice of the holding institution: if a two-volume manuscript like Vat. lat. 630 has only one shelf-mark, it is counted as one manuscript, if each volume as a separate shelf-mark as in the case of Pal. lat. 585 and Pal. lat. 586, they are treated as two manuscripts.
For codices disiecta, composite manuscripts, and multi-volume manuscripts, see also the respective categories in Category:Manuscripts by codicological properties.
Lost manuscripts
Manuscripts that are lost, destroyed, or the fate of which is unknown, still are treated like other manuscripts. Normally, the lemma refers to the last known collection the manuscript was part of. On historic place names, see below.
Erroneous shelfmarks
All manuscripts are cited by their correct current shelfmark. However, if erroneous shelfmarks are found frequently in the literature, either a redirect or even a short article under the wrong lemma may be in order so that users looking for the shelfmark they found elsewhere are redirected to the correct article, where the error should be briefly discussed.
Place names
Place names are generally in the local language, which in some multi-language countries can be mildly delicate to determine. Brussels and Luxembourg are treated as francophone for the purpose of this list, so it's Bruxelles (not Brussel) and Luxembourg (not Lëtzebuerg). Catalan cities are referenced in Catalan, hence La Seu d’Urgell, not Urgel, and so on. In Switzerland, place name follow the language actually spoken locally, although this of course may change over time (so Sion, not Sitten). In the case of non-Latin alphabets, the conventional English rendering of the local place name is used (Saint Petersburg for Санкт-Петербург).
In almost all cases, official names (and abbreviations) are used; the only exception from the latter rule is The Hague, which is rendered Den Haag (not 's-Gravenhage). Also, although Latin is the official language of the Vatican, it is referred to as Città del Vaticano in this Wiki, following common practice.
Needless to say, normally we use current place names. Historic place names may be mentioned in the respective articles, if this helps to avoid confusion, especially if the old name is used in the scholarly literature (e.g. Châlons-sur-Marne, the pre-1997 name of Châlons-en-Champagne). In the case of historic libraries that do no longer exist, the place name at the time of their existence should be used; hence Königsberg for the pre-1945 holdings of the local Staats- und Universitätsbibliothek.
If in doubt, go for the name predominantely used in scholarly literature and leave a redirect for any other options you think relevant.
Names of holding institutions
The same guidelines apply to the names of libraries and archives; official names are used, which normally are in the local language. For details and exceptions, see above.
As with place names, we almost always use the current name and abbreviation, so it's Archivio Apostolico (not Segreto), the universities of Leiden and Gent have a universiteitsbibliotheek (but no longer are rijksuniversiteiten), and so on.
For some libraries, conventional abbreviations are used; again, preference is given to the current official form: BnF (not BN), KBR (not Bibliothèque royale), and so on. In practice, abbreviations are only use for some national libraries (Berlin, Florence, Madrid, Paris, Rome, Vatican, Vienna) plus a few major libraries like the Biblioteca Medicea Laurenziana (BML), the Bayerische Staatsbibliothek (BSB), and the Herzog-August-Bibliothek (HAB). Additionally, for a few libraries with very long official names more conventional short forms of the names have been used in the lemma. If you write an article on a manuscript, please check how the holding institution is referred to in the List of manuscripts; if in doubt, use the official name.
French municipal libraries are a special case. They are always referred to as BM whatever the current designation may be (they tend to change every now and then). The official names, including historic names, are given in the article about the respective library; identifiers such as ISIL codes in the infobox should help to ease any possible confusion.
Shelfmarks and proper names
All manuscripts are referenced by their current shelfmark in the Clavis Wiki; for olim shelfmarks, see below. Only the current shelfmark is part of the lemma, any other information can be discussed in the article itself.
The difference between shelfmark, accession number, and call number is normally irrelevant for our manuscript; catalogue numbers, which are sometimes used in scholarship to reference manuscripts, can and should be cited if this is common practice in the literature on the manuscript in question. Sometimes, catalogue numbers can be become call numbers, as in the case Bamberg.
As for the spelling, a sometimes frustrating variety can be observed (with or without "MS" and the like, with or without spaces, Roman versus Arab numbers, capitalisation, degree of abbreviation, sometimes choice of language). Normally, we follow Kéry. If you are uncertain about the correct shelf mark, look at existing articles and/or the usage of the holding library. Again, redirects can help to deal with multiple forms used in the scholarly literature.
Some manuscripts are know by proper names, and many have sigla in the scholarly literature. Such information can be provided in the article; if proper names are widely spread, a redirect can be useful (e.g. Codex Aemilianensis), and if need be, a disambiguation site can be created.
Very few manuscripts have no shelfmark at all; in these cases, we use sine numero instead of the shelfmark in the lemma.
Previous collections and olim shelfmarks
References to manuscripts should always (not only in the lemma) be based on the current location of the manuscript and the current shelfmark. Previous collections and olim shelf marks can and should be mentioned in the article. In some cases, redirects are used so that users looking for manuscripts that have moved can easily find the correct article (and the current holding institution). For example, Wien, ÖNB, Cod. 16 redirects to Napoli, Biblioteca Nazionale, ex Vind. lat. 2.
Sometimes, it can be surprisingly difficult to establish what the current shelfmark is; such cases should be discussed in the respective article. Also, if a manuscript is referred to by erronous shelfmarks, this should be mentioned at least in more prominent cases, and if the error is wide-spread, a redirect page may be in order. See, for example, the article on Torino, BNU, E.V.44 (including the redirect Torino, BNU, E.V.33).
For manuscripts that are no longer extant, but about which we know enough to cover them in the Clavis Wiki, the last holding institution is relevant for the lemma; this applies, for example, to many Chartrain manuscripts like Chartres, BM, 161.
Where the current location of a manuscript is unknown, the name and shelf mark in the collection the manuscript was kept in last is used for the sake of references, and information on its current whereabouts are provided in the article. The Cheltenham manuscripts are a special case; while those today in public libraries are listed under their current shelfmarks, those in private collections are routinely cited by their Phillipps numbers, so it sometimes makes sense to list them under "Cheltenham" (e.g. Cheltenham, Phillipps Collection, 17849).