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refer(1)                 General Commands Manual                refer(1)

Name         top

       refer - process bibliographic references for groff

Synopsis         top

       refer [-bCenPRS] [-a n] [-B field.macro] [-c fields] [-f n]
             [-i fields] [-k field] [-l range-expression] [-p database-
             file] [-s fields] [-t n] [file ...]

       refer --help

       refer -v
       refer --version

Description         top

       The GNU implementation of refer is part of the groff(1) document
       formatting system.  refer is a troff(1) preprocessor that
       prepares bibliographic citations by looking up keywords specified
       in a roff(7) input document, obviating the need to type such
       annotations, and permitting the citation style in formatted
       output to be altered independently and systematically.  It copies
       the contents of each file to the standard output stream, except
       that it interprets lines between .[ and .] as citations to be
       translated into groff input, and lines between .R1 and .R2 as
       instructions regarding how citations are to be processed.  refer
       interprets and generates roff lf requests so that file names and
       line numbers in messages produced by commands that read its
       output correctly describe the source document.  Normally, refer
       is not executed directly by the user, but invoked by specifying
       the -R option to groff(1).  If no file operands are present, or
       if file is “-”, refer reads the standard input stream.

       A citation identifies a work by reference to a bibliographic
       record detailing it.  Select a work from a database of records by
       listing keywords that uniquely identify its entry.
       Alternatively, a document can specify a record for the work at
       the point its citation occurs.  A document can use either or both
       strategies as desired.

       For each citation, refer produces a mark in the text, like a
       superscripted footnote number or “[Lesk1978a]”.  A mark consists
       of a label between brackets.  The mark can be separated from
       surrounding text and from other labels in various ways.  refer
       produces roff language requests usable by a document or a macro
       package such as me, mm, mom, or ms to produce a formatted
       reference for each citation.  A citation's reference can be
       output immediately after it occurs (as with footnotes), or
       references may accumulate, with corresponding output appearing
       later in the document (as with endnotes).  When references
       accumulate, multiple citations of the same reference produce a
       single formatted entry.

       Interpretation of lines between .R1 and .R2 tokens as
       preprocessor commands is a GNU refer extension.  Documents
       employing this feature can still be processed by AT&T refer by
       adding the lines
              .de R1
              .ig R2
              ..
       to the beginning of the document.  The foregoing input causes
       troff to ignore everything between .R1 and .R2.  The effects of
       some refer commands can be achieved by command-line options;
       these are supported for compatibility with AT&T refer.  It is
       usually more convenient to use commands.

   Bibliographic records
       A bibliographic record describes a referenced work in sufficient
       detail that it may be cited to accepted standards of scholarly
       and professional clarity.  The record format permits annotation
       and extension that a document may use or ignore.  A record is a
       plain text sequence of fields, one per line, each consisting of a
       percent sign %, an alphanumeric character classifying it, one
       space, and its contents.  If a field's contents are empty, the
       field is ignored.

       Frequently, such records are organized into a bibliographic
       database, with each entry separated by blank lines or file
       boundaries.  This practice relieves documents of the need to
       maintain bibliographic data themselves.  The programs lookbib(1)
       and lkbib(1) consult a bibliographic database, and indxbib(1)
       indexes one to speed retrieval from it, reducing document
       processing time.  Use of these tools is optional.

       The conventional uses of the bibliographic field entries are as
       follows.  Within a record, fields other than %A and %E replace
       previous occurrences thereof.  The ordering of multiple %A and %E
       fields is significant.

       %A     names an author.  If the name contains a suffix such as
              “Jr.” or “III”, it should be separated from the surname by
              a comma.  We recommend always supplying an %A field or a
              %Q field.

       %B     records the title of the book within which a cited article
              is collected.  See %J and %T.

       %C     names the city or other place of publication.

       %D     indicates the date of publication.  Specify the year in
              full.  If the month is specified, use its name rather than
              its number; only the first three letters are required.  We
              recommend always supplying a %D field; if the date is
              unknown, use “in press” or “unknown” as its contents.

       %E     names an editor of the book within which a cited article
              is collected.  Where a work has editors but no authors,
              name the editors in %A fields and append “, (ed.)” or
              “, (eds.)” to the last of these.

       %G     records the U.S. government ordering number, ISBN, DOI, or
              other unique identifier.

       %I     names the publisher (issuer).

       %J     records the title of the journal within which a cited
              article is collected.  See %B and %T.

       %K     lists keywords intended to aid searches.

       %L     is a label; typically unused in database entries, it can
              override the label format otherwise determined.

       %N     records the issue number of the journal within which a
              cited article is collected.

       %O     presents additional (“other”) information, typically
              placed at the end of the reference.

       %P     lists the page numbers of a cited work that is part of a
              larger collection.  Specify a range with m-n.

       %Q     names an institutional author when no %A fields are
              present.  Only one %Q field is permitted.

       %R     is an identifier for a report, thesis, memorandum, or
              other unpublished work.

       %S     records the title of a series to which the cited work
              belongs.

       %T     is the work's title.  See %B and %J.

       %V     is the volume number of the journal or book containing the
              cited work.

       %X     is an annotation.  By convention, it is not formatted in
              the citing document.

       If the obsolescent “accent strings” feature of the ms or me macro
       packages is used, such strings should follow the character to be
       accented; an ms document must call the AM macro before using
       them.  Do not quote accent strings: use one \ rather than two.
       See groff_char(7) for a modern approach to the problem of
       diacritics.

   Citations
       Citations have a characteristic format.
              .[opening-text
              flags keyword ...
              field
              ...
              .]closing-text

       opening-text, closing-text, and flags are optional, and only one
       keyword or field need be specified.  If keywords are present,
       refer searches the bibliographic database(s) for a unique
       reference matching them.  Multiple matches are an error; add more
       keywords to disambiguate the reference.  In the absence of
       keywords, fields constitute the bibliographic record.  Otherwise,
       fields specify additional data to replace or supplement those in
       the reference.  When references are accumulating and keywords are
       present, specify additional fields at most on the first citation
       of a particular reference; they apply to all further citations
       thereof.

       opening-text and closing-text are roff input used to bracket the
       label, overriding the bracket-label command.  Leading and
       trailing spaces are significant.  If either of these is non-
       empty, the corresponding arguments to the bracket-label command
       are not used; alter this behavior with the [ and ] flags.

       flags is a list of non-alphanumeric characters each of which
       modifies the treatment of the particular citation.  AT&T refer
       treats these flags as keywords, but ignores them since they are
       non-alphanumeric.  The following flags direct GNU refer.

       #      Use the label specified by the short-label command, if
              any.  refer otherwise uses the normal label.  Typically, a
              short label implements author-date citation styles
              consisting of a name, a year, and a disambiguating letter
              if necessary.  “#” is meant to suggest such a
              (quasi-)numeric label.

       [      Precede opening-text with the first argument given to the
              bracket-label command.

       ]      Follow closing-text with the second argument given to the
              bracket-label command.

       An advantage of the [ and ] flags over use of opening-text and
       closing-text is that you can update the document's bracketing
       style in one place using the bracket-label command.  Another is
       that sorting and merging of citations is not necessarily
       inhibited if the flags are used.

       refer appends any label resulting from a citation to the roff
       input line preceding the .[ token.  If there is no such line,
       refer issues a warning diagnostic.

       There is no special notation for citing multiple references in
       series.  Use a sequence of citations, one for each reference,
       with nothing between them.  refer attaches all of their labels to
       the line preceding the first.  These labels may be sorted or
       merged.  See the description of the <> label expression, and of
       the sort-adjacent-labels and abbreviate-label-ranges commands.  A
       label is not merged if its citation has a non-empty opening-text
       or closing-text.  However, the labels for two adjacent citations,
       the former using the ] flag and without any closing-text, and the
       latter using the [ flag and without any opening-text, may be
       sorted and merged even if the former's opening-text or the
       latter's closing-text is non-empty.  (To prevent these
       operations, use the dummy character escape sequence \& as the
       former's closing-text.)

   Commands
       Commands are contained between lines starting with .R1 and .R2.
       The -R option prevents recognition of these lines.  When a refer
       encounters a .R1 line, it flushes any accumulated references.
       Neither .R1 nor .R2 lines, nor anything between them, is output.

       Commands are separated by newlines or semicolons.  A number sign
       (#) introduces a comment that extends to the end of the line, but
       does not conceal the newline.  Each command is broken up into
       words.  Words are separated by spaces or tabs.  A word that
       begins with a (neutral) double quote (") extends to the next
       double quote that is not followed by another double quote.  If
       there is no such double quote, the word extends to the end of the
       line.  Pairs of double quotes in a word beginning with a double
       quote collapse to one double quote.  Neither a number sign nor a
       semicolon is recognized inside double quotes.  A line can be
       continued by ending it with a backslash “\”; this works
       everywhere except after a number sign.

       Each command name that is marked with * has an associated
       negative command no-name that undoes the effect of name.  For
       example, the no-sort command specifies that references should not
       be sorted.  The negative commands take no arguments.

       In the following description each argument must be a single word;
       field is used for a single upper or lower case letter naming a
       field; fields is used for a sequence of such letters; m and n are
       used for a non-negative numbers; string is used for an arbitrary
       string; file is used for the name of a file.

       abbreviate* fields string1 string2 string3 string4
              Abbreviate the first names of fields.  An initial letter
              will be separated from another initial letter by string1,
              from the surname by string2, and from anything else (such
              as “von” or “de”) by string3.  These default to a period
              followed by a space.  In a hyphenated first name, the
              initial of the first part of the name will be separated
              from the hyphen by string4; this defaults to a period.  No
              attempt is made to handle any ambiguities that might
              result from abbreviation.  Names are abbreviated before
              sorting and before label construction.

       abbreviate-label-ranges* string
              Three or more adjacent labels that refer to consecutive
              references will be abbreviated to a label consisting of
              the first label, followed by string, followed by the last
              label.  This is mainly useful with numeric labels.  If
              string is omitted, it defaults to “-”.

       accumulate*
              Accumulate references instead of writing out each
              reference as it is encountered.  Accumulated references
              will be written out whenever a reference of the form
                     .[
                     $LIST$
                     .]
              is encountered, after all input files have been processed,
              and whenever a .R1 line is recognized.

       annotate* field string
              field is an annotation; print it at the end of the
              reference as a paragraph preceded by the line

                     .string

              If string is omitted, it will default to AP; if field is
              also omitted it will default to X.  Only one field can be
              an annotation.

       articles string ...
              Each string is a definite or indefinite article, and
              should be ignored at the beginning of T fields when
              sorting.  Initially, “a”, “an”, and “the” are recognized
              as articles.

       bibliography file ...
              Write out all the references contained in each
              bibliographic database file.  This command should come
              last in an .R1/.R2 block.

       bracket-label string1 string2 string3
              In the text, bracket each label with string1 and string2.
              An occurrence of string2 immediately followed by string1
              will be turned into string3.  The default behavior is as
              follows.
                     bracket-label \*([. \*(.] ", "

       capitalize fields
              Convert fields to caps and small caps.

       compatible*
              Recognize .R1 and .R2 even when followed by a character
              other than space or newline.

       database file ...
              Search each bibliographic database file.  For each file,
              if an index file.i created by indxbib(1) exists, then it
              will be searched instead; each index can cover multiple
              databases.

       date-as-label* string
              string is a label expression that specifies a string with
              which to replace the D field after constructing the label.
              See subsection “Label expressions” below for a description
              of label expressions.  This command is useful if you do
              not want explicit labels in the reference list, but
              instead want to handle any necessary disambiguation by
              qualifying the date in some way.  The label used in the
              text would typically be some combination of the author and
              date.  In most cases you should also use the
              no-label-in-reference command.  For example,
                     date-as-label D.+yD.y%a*D.-y
              would attach a disambiguating letter to the year part of
              the D field in the reference.

       default-database*
              The default database should be searched.  This is the
              default behavior, so the negative version of this command
              is more useful.  refer determines whether the default
              database should be searched on the first occasion that it
              needs to do a search.  Thus a no-default-database command
              must be given before then, in order to be effective.

       discard* fields
              When the reference is read, fields should be discarded; no
              string definitions for fields will be output.  Initially,
              fields are XYZ.

       et-al* string m n
              Configure use of “et al” in the evaluation of @
              expressions in label expressions.  If u is the number of
              authors needed to make the author sequence unambiguous and
              the total number of authors is t, then the last t-u
              authors will be replaced by string provided that t-u is
              not less than m and t is not less than n.  The default
              behavior is as follows.
                     et-al " et al" 2 3
              Note the absence of a dot from the end of the
              abbreviation, which is arguably not correct.  (Et al[.]
              is short for et alli, as etc. is short for et cetera.)

       include file
              Include file and interpret the contents as commands.

       join-authors string1 string2 string3
              Join multiple authors together with strings.  When there
              are exactly two authors, they will be joined with string1.
              When there are more than two authors, all but the last two
              will be joined with string2, and the last two authors will
              be joined with string3.  If string3 is omitted, it will
              default to string1; if string2 is also omitted it will
              also default to string1.  For example,
                     join-authors " and " ", " ", and "
              will restore the default method for joining authors.

       label-in-reference*
              When outputting the reference, define the string [F to be
              the reference's label.  This is the default behavior, so
              the negative version of this command is more useful.

       label-in-text*
              For each reference output a label in the text.  The label
              will be separated from the surrounding text as described
              in the bracket-label command.  This is the default
              behavior, so the negative version of this command is more
              useful.

       label string
              string is a label expression describing how to label each
              reference.

       separate-label-second-parts string
              When merging two-part labels, separate the second part of
              the second label from the first label with string.  See
              the description of the <> label expression.

       move-punctuation*
              In the text, move any punctuation at the end of line past
              the label.  We recommend employing this command unless you
              are using superscripted numbers as labels.

       reverse* string
              Reverse the fields whose names are in string.  An optional
              integer after a field name limits the number of such
              fields to the given count; no integer means no limit.

       search-ignore* fields
              While searching for keys in databases for which no index
              exists, ignore the contents of fields.  Initially, fields
              XYZ are ignored.

       search-truncate* n
              Only require the first n characters of keys to be given.
              In effect when searching for a given key words in the
              database are truncated to the maximum of n and the length
              of the key.  Initially, n is 6.

       short-label* string
              string is a label expression that specifies an alternative
              (usually shorter) style of label.  This is used when the #
              flag is given in the citation.  When using author-date
              style labels, the identity of the author or authors is
              sometimes clear from the context, and so it may be
              desirable to omit the author or authors from the label.
              The short-label command will typically be used to specify
              a label containing just a date and possibly a
              disambiguating letter.

       sort* string
              Sort references according to string.  References will
              automatically be accumulated.  string should be a list of
              field names, each followed by a number, indicating how
              many fields with the name should be used for sorting.  “+”
              can be used to indicate that all the fields with the name
              should be used.  Also . can be used to indicate the
              references should be sorted using the (tentative) label.
              (Subsection “Label expressions” below describes the
              concept of a tentative label.)

       sort-adjacent-labels*
              Sort labels that are adjacent in the text according to
              their position in the reference list.  This command should
              usually be given if the abbreviate-label-ranges command
              has been given, or if the label expression contains a <>
              expression.  This has no effect unless references are
              being accumulated.

   Label expressions
       Label expressions can be evaluated both normally and tentatively.
       The result of normal evaluation is used for output.  The result
       of tentative evaluation, called the tentative label, is used to
       gather the information that normal evaluation needs to
       disambiguate the label.  Label expressions specified by the
       date-as-label and short-label commands are not evaluated
       tentatively.  Normal and tentative evaluation are the same for
       all types of expression other than @, *, and % expressions.  The
       description below applies to normal evaluation, except where
       otherwise specified.

       field [n]
              is the nth part of field.  If n is omitted, it defaults
              to 1.

       'string'
              The characters in string literally.

       @      All authors joined as specified by the join-authors
              command.  The whole of each author's name is used.
              However, if the references are sorted by author (that is,
              the sort specification starts with “A+”), then authors'
              surnames will be used instead, provided that this does not
              introduce ambiguity, and also an initial subsequence of
              the authors may be used instead of all the authors, again
              provided that this does not introduce ambiguity.  Given
              any two referenced works with n authors, the use of only
              the surname for the nth author of a reference is regarded
              as ambiguous if the other reference shares the first n-1
              authors, the nth authors of each reference are not
              identical, but the nth authors' surnames are the same.  A
              proper initial subsequence of the sequence of authors for
              some reference is considered to be ambiguous if there is a
              reference with some other sequence of authors which also
              has that subsequence as a proper initial subsequence.
              When an initial subsequence of authors is used, the
              remaining authors are replaced by the string specified by
              the et-al command; this command may also specify
              additional requirements that must be met before an initial
              subsequence can be used.  @ tentatively evaluates to a
              canonical representation of the authors, such that authors
              that compare equally for sorting purposes have the same
              representation.

       %n
       %a
       %A
       %i
       %I     The serial number of the reference formatted according to
              the character following the %.  The serial number of a
              reference is 1 plus the number of earlier references with
              same tentative label as this reference.  These expressions
              tentatively evaluate to an empty string.

       expr*  If there is another reference with the same tentative
              label as this reference, then expr, otherwise an empty
              string.  It tentatively evaluates to an empty string.

       expr+n
       expr-n The first (+) or last (-) n upper or lower case letters or
              digits of expr.  roff special characters (such as \('a)
              count as a single letter.  Accent strings are retained but
              do not count towards the total.

       expr.l expr converted to lowercase.

       expr.u expr converted to uppercase.

       expr.c expr converted to caps and small caps.

       expr.r expr reversed so that the surname is first.

       expr.a expr with first names abbreviated.  Fields specified in
              the abbreviate command are abbreviated before any labels
              are evaluated.  Thus .a is useful only when you want a
              field to be abbreviated in a label but not in a reference.

       expr.y The year part of expr.

       expr.+y
              The part of expr before the year, or the whole of expr if
              it does not contain a year.

       expr.-y
              The part of expr after the year, or an empty string if
              expr does not contain a year.

       expr.n The surname part of expr.

       expr1~expr2
              expr1 except that if the last character of expr1 is - then
              it will be replaced by expr2.

       expr1 expr2
              The concatenation of expr1 and expr2.

       expr1|expr2
              If expr1 is non-empty then expr1 otherwise expr2.

       expr1&expr2
              If expr1 is non-empty then expr2 otherwise an empty
              string.

       expr1?expr2:expr3
              If expr1 is non-empty then expr2 otherwise expr3.

       <expr> The label is in two parts, which are separated by expr.
              Two adjacent two-part labels which have the same first
              part will be merged by appending the second part of the
              second label onto the first label separated by the string
              specified in the separate-label-second-parts command
              (initially, a comma followed by a space); the resulting
              label will also be a two-part label with the same first
              part as before merging, and so additional labels can be
              merged into it.  It is permissible for the first part to
              be empty; this may be desirable for expressions used in
              the short-label command.

       (expr) The same as expr.  Used for grouping.

       The above expressions are listed in order of precedence (highest
       first); & and | have the same precedence.

   Macro interface
       Each reference starts with a call to the macro ]-.  The string [F
       will be defined to be the label for this reference, unless the
       no-label-in-reference command has been given.  There then follows
       a series of string definitions, one for each field: string [X
       corresponds to field X.  The register [P is set to 1 if the P
       field contains a range of pages.  The [T, [A and [O registers are
       set to 1 according as the T, A and O fields end with any of .?!
       (an end-of-sentence character).  The [E register will be set to 1
       if the [E string contains more than one name.  The reference is
       followed by a call to the ][ macro.  The first argument to this
       macro gives a number representing the type of the reference.  If
       a reference contains a J field, it will be classified as type 1,
       otherwise if it contains a B field, it will be type 3, otherwise
       if it contains a G or R field it will be type 4, otherwise if it
       contains an I field it will be type 2, otherwise it will be
       type 0.  The second argument is a symbolic name for the type:
       other, journal-article, book, article-in-book, or tech-report.
       Groups of references that have been accumulated or are produced
       by the bibliography command are preceded by a call to the ]<
       macro and followed by a call to the ]> macro.

Options         top

       --help displays a usage message, while -v and --version show
       version information; all exit afterward.

       -R     Don't recognize lines beginning with .R1/.R2.

       Other options are equivalent to refer commands.

       -a n   reverse An

       -b     no-label-in-text; no-label-in-reference

       -B     See below.

       -c fields
              capitalize fields

       -C     compatible

       -e     accumulate

       -f n   label %n

       -i fields
              search-ignore fields

       -k     label L~%a

       -k field
              label field~%a

       -l     label A.nD.y%a

       -l m   label A.n+mD.y%a

       -l ,n  label A.nD.y-n%a

       -l m,n label A.n+mD.y-n%a

       -n     no-default-database

       -p db-file
              database db-file

       -P     move-punctuation

       -s spec
              sort spec

       -S     label "(A.n|Q) ', ' (D.y|D)"; bracket-label " (" ) "; "

       -t n   search-truncate n

       The B option has command equivalents with the addition that the
       file names specified on the command line are processed as if they
       were arguments to the bibliography command instead of in the
       normal way.

       -B     annotate X AP; no-label-in-reference

       -B field.macro
              annotate field macro; no-label-in-reference

Environment         top

       REFER  Assign this variable a file name to override the default
              database.

Files         top

       /usr/dict/papers/Ind
              Default database.

       file.i Index files.

       /usr/local/share/groff/1.23.0/tmac/refer.tmac
              defines macros and strings facilitating integration with
              macro packages that wish to support refer.

       refer uses temporary files.  See the groff(1) man page for
       details of where such files are created.

Bugs         top

       In label expressions, <> expressions are ignored inside .char
       expressions.

Examples         top

       We can illustrate the operation of refer with a sample
       bibliographic database containing one entry and a simple roff
       document to cite that entry.

              $ cat > my-db-file
              %A Daniel P.\& Friedman
              %A Matthias Felleisen
              %C Cambridge, Massachusetts
              %D 1996
              %I The MIT Press
              %T The Little Schemer, Fourth Edition
              $ refer -p my-db-file
              Read the book
              .[
              friedman
              .]
              on your summer vacation.
              <Control+D>
              .lf 1 -
              Read the book\*([.1\*(.]
              .ds [F 1
              .]-
              .ds [A Daniel P. Friedman and Matthias Felleisen
              .ds [C Cambridge, Massachusetts
              .ds [D 1996
              .ds [I The MIT Press
              .ds [T The Little Schemer, Fourth Edition
              .nr [T 0
              .nr [A 0
              .][ 2 book
              .lf 5 -
              on your summer vacation.

       The foregoing shows us that refer (a) produces a label “1”; (b)
       brackets that label with interpolations of the “[.”  and “.]”
       strings; (c) calls a macro “]-”; (d) defines strings and
       registers containing the label and bibliographic data for the
       reference; (e) calls a macro “][”; and (f) uses the lf request to
       restore the line numbers of the original input.  As discussed in
       subsection “Macro interface” above, it is up to the document or a
       macro package to employ and format this information usefully.
       Let us see how we might turn groff_ms(7) to this task.

              $ REFER=my-db-file groff -R -ms
              .LP
              Read the book
              .[
              friedman
              .]
              on your summer vacation.
              Commentary is available.\*{*\*}
              .FS \*{*\*}
              Space reserved for penetrating insight.
              .FE

       ms's automatic footnote numbering mechanism is not aware of
       refer's label numbering, so we have manually specified a
       (superscripted) symbolic footnote for our non-bibliographic
       aside.

See also         top

       “Refer — A Bibliography System”, by Bill Tuthill, 1983, Computing
       Services, University of California, Berkeley.

       “Some Applications of Inverted Indexes on the Unix System”, by M.
       E. Lesk, 1978, AT&T Bell Laboratories Computing Science Technical
       Report No. 69.

       indxbib(1), lookbib(1), lkbib(1)

COLOPHON         top

       This page is part of the groff (GNU troff) project.  Information
       about the project can be found at 
       ⟨http://www.gnu.org/software/groff/⟩.  If you have a bug report
       for this manual page, see ⟨http://www.gnu.org/software/groff/⟩.
       This page was obtained from the project's upstream Git repository
       ⟨https://git.savannah.gnu.org/git/groff.git⟩ on 2023-12-22.  (At
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       problems in this HTML version of the page, or you believe there
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groff 1.23.0.453-330f9-d... 22 December 2023                    refer(1)