## Formatting entries

As of the winter 1992 release, the bibliography has been converted to bibtex. Up to this time the bibliography had (for historical reasons) been more or less in the format of the old "refer" program designed as a citation system for troff. Special thanks to volunteers Jeff Erickson, Robert Freimer, and Peter Yamamoto, who took the initiative of developing quality conversion software to meet our situation.

Because of the distributed nature of updates, it seems desirable to have some written guidelines for the format of entries, in order that the final product have a consistent style. The following suggestions are based on common practice where discernible, established authorities where possible, and personal opinion where unavoidable.

You will likely find existing entries in disagreement with these guidelines. Either the entry or the guidelines should be fixed. If some entry can't be decently handled by the current guidelines, or you think they're just plain wrong in any case, please let us know about it.

In the hope of keeping future input work reasonably simple and error-free, a few lexical conventions were set at the time of bibtex conversion, as follows. Where possible you should use lower case (for simplicity), a leading comma ", volume = 12" (to make missing commas obvious), and put all text for a field on a single line (to avoid spending time on prettyprinting). If you must break lines, such as in the abstract= or annote= or comments= or note= fields, start subsequent lines with a tab.

Special characters and diacriticals should be entered as specified on p.52 of the TeXbook. The common single-letter ones are described below.

   \'  acute           sup{\'e}rieur    {\'O}'D{\'u}nlaing   [\*' in troff -ms]
\  grave           probl{\e}me     Bruy{\e}re          [\* in troff -ms]
\^  circumflex      m{\^e}me         L'H{\^o}pital        [\*' in troff -ms]
\~  tilde           ma{\~n}ana       N{\'u}{\~n}ez        [\*' in troff -ms]
\v  hacek           h{\'a}{\v c}ek   Matou{\v s}ek        [\*C in troff -ms]
\c  cedilla         fran{\c c}ais    {\'S}wi{\c a}tek     [\*, in troff -ms]
\"  umlaut          f{\"u}r          G{\"u}ting           [\*: in troff -ms]
\H  Hung. umlaut                     Erd{\H o}s           [R.I.P. 96.09.20]
\i  dotless i                        D{\'\i}az            where accented
\j  dotless j                                             where accented

Note that diacriticals precede the letter affected. A complication is that in tex, control sequences specified using letters must somehow be separated from the ordinary letters that follow. A simple way is to use spaces as in "Erd\H os", but this will look like two separate words to bibtex. Another is to use braces as in "Erd\H{o}s", but this too is confounded by bibtex, which (1) normally wants to decapitalize text in titles not protected by braces, to support variant capitalization styles, and (2) will interpret an umlaut \" as the end of a quoted string, unless specially protected.

Initially it might seem enough to put braces around the whole word when it contains either a fussy diacritical or (in a title field) a capital letter. However, it turns out that, because of how it handles the author field, bibtex dictates the convention to follow. Since adding a feature to recognize and handle accented characters in author fields (for benefit of the alpha bibliography styles), bibtex requires that we "place the entire accented character in braces; in this case either {\"o} or {\"{o}} will do .... furthermore these braces must not themselves be enclosed in braces (other than the ones that might delimit the entire field or the entire entry), and there must be a backslash as the very first character inside the braces". Thus you should use, for example, {\'O}'D{\'u}nlaing, Matou{\v s}ek, G{\"u}ting, and Erd{\H o}s, and we recommend that for consistency you treat all accents this way in whatever bibtex fields they appear. However you will further have to embrace the whole of any capitalized name that appears in a title field. C'est la vie {BibTeXienne}.

A few hacks deserve mention. The macro \path, from path.sty, helps with transparency and linebreaking of network pathnames like \path|http://hamster.cs.uni-sb.de/~eckstein/publications/FB14-95-05.ps.Z|, and should be used whenever they appear in regular text. (path.sty is part of the Eplain package, and is being used when typesetting the url field for geom.ps.) Tex ties like ~ and "\ " should be avoided in regular text, as bibtex undertakes to insert them where appropriate.

Mathematical expressions, including numbers in titles, should always be entered in tex notation. Author, title, and page information from other than the title page of the paper itself is untrustworthy: you might want to do data entry from a proceedings table of contents for speed, but please take time to proofread against title pages for accuracy.

Below is a quick naming of parts for entries in the database, with discussions of the conventions that have evolved. More detailed information on entry formats can be found in the bibtex documentation.

### Entry type:

We ignore some of the fine distinctions available in bibtex and map most everything onto the types of article, book, inbook, incollection, inproceedings, mastersthesis, phdthesis, and techreport. Preprints (a.k.a. "Manuscripts") are considered unnumbered techreports for our purposes, since they are often later distributed in that form. If present entries in the bibliography are any guide, you should rarely need other entry types. In particular, note that low-grade items like personal communications should not be included since our charter is to cover only openly available materials. If you need such an entry in your papers' reference lists, please keep it in a supplementary bibliography file until it is published. For example, "\bibliography{mine,mygroup,geom}" specifies a search path of three files bibtex can use to satisfy references.

### Citation tag:

It's easy to come up with citetags that are mnemonic, short, or unique, but not to have all three at the same time. The system we use is a compromise. Our citetags consist of an author part (first letter of surname of each author), a title part (first letter or digit string of each significant word in the title, up to 5 characters), and a year part (last two digits of year of publication), separated by dashes. Connecting words like auf, da, de, der, van, von are considered part of the surname if and only if they are capitalized. Thus "J. O'Rourke, Art Gallery Theorems and Algorithms, 1987" reduces to "o-agta-87". The tricky part of this is how to define "significant" words of the title, particularly when punctuation and mathematical strings are involved. Here are the formal rules, which are intended to produce a commonsense result as often as possible:
• ignore these words (most common short English articles, conjunctions, and prepositions): "a" "among" "an" "and" "as" "at" "by" "for" "from" "in" "into" "of" "on" "or" "over" "than" "the" "to" "under" "via" "with"
• convert Roman numerals to Arabic, remove diacriticals, braces, and font-changing commands (like \it), remove quotes and apostrophes, convert other punctuation outside math delimiters $...$ to spaces
• retain only the first alpha/numeric token within $...$ delimiters
• take the first letter, or first digit string, of remaining words
• take the first 5 characters so produced
For example, "fran{\c c}ais" and "$\log n-1$" are each one word while "$k$th-nearest" is two, and the abbreviation of "{${\rm SEPARATION}^{\rm TM}$} and $(\leq k)$-levels IV: A silly example" is "sll4s".

To make the result more intuitive, we break the rules in the following cases:

• "\varepsilon" becomes "e"
• "on-line" and "online" become "ol" instead of "l" and "o" respectively.
• "2d" becomes "2d" instead of "2" (similarly for "1d", "3d" etc)
For just under 99% of entries the citetag generated by this procedure will not conflict with that of any existing entry. But if it does, you'll have to find some way to break the tie. In our experience, collisions at this stage have come about only from various forms of the same paper'' conflicting with each other, and one of the following tiebreaking rules suffices:
• for multipart papers, add the part number, in Arabic, to the title field (c-lbors1-90, c-lbors2-90)
• for other variations on a theme, add a letter from a distinguishing word to the title field (s-mmdpsl-90, s-mmdpsp-90)
• for alternate publications of a paper, append "a" for article, "i" for incollection or inbook or inproceedings, or "t" for techreport, to the year field (kkt-ptots-90i, kkt-ptots-90t)
• otherwise, punt and discriminate using whatever you can (g-gramq-cga-88, g-gramq-edbt-88)
If the resulting citetags don't match your favourite descriptor for the reference, you can still use the old familiar version if you declare a mapping between the two in your tex source, such as the following:
\newcommand{\smawk}{akmsw-gamsa-87}
Entry citetags should be mostly stable once assigned, but may be changed in the direction of correctness, or to resolve conflicts. You needn't bother creating citetags for entries you don't cite: just leave the tag part empty. The merging software will automatically generate citetags for contributed entries lacking them. It also rewrites conference and journal names to standard form, does prettyprinting, and keeps entries in the geom.bib file sorted in order of author, title, and year, all the better to bring various appearances of the same paper together. (This should match the order of the default softcopy.)

### Fields:

We inherit most fields from the bibtex standard styles, as well as common extensions like abstract=, annote=, isbn=, language=. Fields cites=, comments=, keywords=, precedes=, succeeds=, update=, and url= are our own. Conventions for entering all of these are as follows. Quotes aren't necessary when the field value is entirely digits (true for volume, number, and year, normally). You should use the empty string "" for fields you can't complete just yet (e.g., pages = "" for a conference or journal paper to appear). Some older entries use a visible placeholder like "??"; if you need to cite them, please make an honest effort to fill the hole rather than immediately changing to "".
• abstract: verbatim from the original item (optional)
• encouraged, at least when concise
• use for techreports, theses, obscure publishers, and obscure irregular conferences; otherwise discouraged
• use only first city if publisher lists several
• give English-language name, with correct diacriticals (e.g. Munich rather than M{\"u}nchen, Saarbr{\"u}cken rather than Saarbruecken)
• city/country names to use are those in effect at time of publication (e.g. West and East Germany between 1949 and 3 October 1990, Germany otherwise)
• for @inproceedings items, an address without publisher will be presumed by the merging software to be the conference city, and rewritten into the site field
• annote: explanatory or critical comment on item content (optional)
• little used in present entries, but welcomed
• author:
• separate multiple author fields with " and ", order same as in reference
• author's names in normal order, not reversed
• use braces to enclose capitalized or comma-separated elements of a compound surname, e.g. {Van Wyk} or {Lipski, Jr.}
• it is best to enter full given names as used on the title page, but you may follow the custom of mathematical literature and use initials, space-separated (exceptions to avoid collision: Ta. Asano, Te. Asano)
• [van Leunen p.155] by "strict and narrow propriety" we should cite precisely the name which appears on the item, even if it leads to irregularities. While it is reasonable to fix up such typographical glitches (attributable to coauthors, copy editors, and the pressure of deadlines) as you are certain the author would want you to, remaining inconsistencies are the author's worry and not the bibliographer's.
• booktitle: title of book or proceedings containing item
• for English items, capitalize first word, first word after a colon, and all other words except articles and unstressed conjunctions and prepositions. Otherwise follow capitalization conventions of the native language, if you know them. (According to the MLA Handbook, for French, German, Italian, Latin, and Spanish, capitalization in titles is the same as in normal prose.) There is no need for braces on capitalized words in this field.
• abbreviations for some popular conferences are in the authority file. The merging software will recognize and convert most variant abbreviations to standard form.
• chapter: chapter or section number, where item is part of a monograph
• use entry type of incollection if chapter has its own title, inbook otherwise
• cites: citations made by item (optional)
• give as list using biblio citetags, such as cites = "bs-dcms-76, gjpt-tsp-78, o-agta-87"
• needn't be an exhaustive copy of the item's citations, but if used should at least give the significant ones. You can say cites = "bs-dcms-76, ..., ZZZ" if the list is exhaustive.
• supplemental information not a part of the reference proper: notes on a item's source language, or relation to other items, or a UMI order number and page count, or a Computing Reviews or Math Reviews number....
• separate multiple comments with a semicolon
• edition: of a book
• use numbered ordinal, e.g. "2nd"
• editor:
• editors of proceedings not needed, and discouraged
• otherwise, use guidelines for author
• institution: publisher of a techreport
• include any relevant department, and list in minor-to-major order (e.g. "Inst. Math., Univ. Nancago")
• isbn: of book (optional)
• issn: of series (optional)
• worthwhile only for obscure or otherwise hard-to-find items
• give with hyphens as specified by publisher
• journal:
• abbreviations for some popular journals are in the authority file. The merging software will recognize and convert most variant abbreviations to standard form.
• separate journal series are considered separate journals, e.g. journal = "J. Combin. Theory Ser. A" rather than series or volume A
• keywords:
• use to supplement, for searching or descriptive purposes, terms already present in the item's title
• separate multiple keyword terms with commas
• keywords need only be attached to the newest of a paper's appearances, if identical for all
• use those in authority file, by preference
• additions to the list of keywords, are expected and welcomed, within reason; send a diff for the authority file at update time
• language: original language of an entry (if not English)
• supported by AMSTex styles, so we might as well
• month: month of publication
• encouraged for techreports and theses, discouraged otherwise
• use bibtex standard abbreviations (three letters, lower case, no quotes)
• note:
• use for supplemental information which should appear in a citing paper's reference list; otherwise use comments field
• e.g. note = "Errata in 2(1981), 105"
• for theses, give techreport type and number, if known, e.g. note = "Report TR-86-103"
• nickname: short name of conference, distinct from booktitle
• e.g. "ISAAC '94"
• best used on an entry for the proceedings itself, where years of publication and conference differ, or where connection between conference and booktitle is obscure; discouraged otherwise
• note:
• use for supplemental information that should appear in a citing paper's reference list; otherwise use comments field
• e.g. note = "Errata in 2(1981), 105" or "Special Issue on Networks"
• for theses, give techreport type and number, if known, e.g. note = "Report TR-86-103"
• number: of techreport, work in a series, or issue of journal
• essential for true techreports (nolle techreportum sine numeratum)
• for journals, necessary iff there exists more than one "page 1" per volume (e.g. proceedings as separately-paginated issue of journal), and discouraged otherwise
• use "--" for combined issues, e.g. "3--4"
• pages:
• use double dash "--" in a number range
• precedes/succeeds: pointer lists for temporal relationships among entries
• for example, precedes = "oy-nubks-88" points to new & improved paper, succeeds = "k-cmgcl-77, k-cmgca-79" is backpointer from it
• publisher:
• school: granting degree, for thesis
• include any relevant department, since this assists inquiries about availability or contents, and list in minor-to-major order (e.g. "Dept. Comput. Sci., Univ. Nancago")
• series: of books
• e.g. "Lecture Notes in Computer Science"
• site: city of conference
• available for those who prefer to record it, but generally discouraged for individual papers (make a separate entry for the proceedings itself)
• title: of item
• for English non-books, you need only capitalize first word and proper names, and enclose latter capitalized words in braces so that bibtex will leave them alone. If you prefer, you may capitalize other words in a title to get full uppers & lowers capitalization, but take care not to embrace them. (Full capitalization is optional because it's more complex, and we know of no journals still requiring it.)
• omit qualifiers like "(extended abstract)"
• [van Leunen p.170] regardless of the style of the original, use colon to separate title from subtitle (edit if necessary): for example change "Serial science. {I}. Definitions" to "Serial science, {I}: Definitions"
• otherwise "correct" only what you're certain the author would want you to
• enclose math expressions (including numbers) in $...$, and express in tex notation; use {$...$} if expression contains capitals
• type: of techreport or thesis
• e.g. "Technical Report" or "Manuscript" or "M.{Phil}. Thesis"
• for theses, give the actual degree name, and supplement with keywords "master thesis" or "doctoral thesis" accordingly
• if the thesis was distributed as a numbered report, then give its type and number in the note= field
• capitalized words after the first need braces in this field
• update: date and bibliographer corresponding to last change
• maintained by the merging software (so you shouldn't touch it)
• url: universal resource locator (from the World-Wide Web project)
• meant to express all manner of location information in a standard and machine-interpretable form, so that plain text documents can contain hypertext pointers to resources across the network. A hypertext browser like Mosaic can retrieve online items, or where older or offline methods are concerned you can retrieve by hand. In both cases the URL is a convenient shorthand. The general syntax is scheme://user:password%host:port/pathname, where the user%, :password, and :port parts are optional to specify values unusual for the particular access scheme. (The URL standard calls for user@, but bibtex treats every @ as beginning a new entry, so we'll have to say user% for now.)

Examples of the most common uses:

• use to flag entries with errors you can't fix just now ("% wrong volume number"), or to flag truthful data that may look erroneous ("% yes, connexion''")