refer(1) — Linux manual page

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refer(1)                   General Commands Manual                  refer(1)

Name         top

       refer - preprocess bibliographic references for groff

Synopsis         top

       refer [-benCPRS] [-a n] [-c fields] [-f n] [-i fields] [-k field]
             [-l m,n] [-p filename] [-s fields] [-t n] -B field.macro [file

       refer --help

       refer -v
       refer --version

Description         top

       This file documents the GNU version of refer, which is part of the
       groff document formatting system.  refer copies the contents of
       filename... to the standard output, except that lines between .[ and
       .] are interpreted as citations, and lines between .R1 and .R2 are
       interpreted as commands about how citations are to be processed.

       Each citation specifies a reference.  The citation can specify a
       reference that is contained in a bibliographic database by giving a
       set of keywords that only that reference contains.  Alternatively it
       can specify a reference by supplying a database record in the
       citation.  A combination of these alternatives is also possible.

       For each citation, refer can produce a mark in the text.  This mark
       consists of some label which can be separated from the text and from
       other labels in various ways.  For each reference it also outputs
       groff commands that can be used by a macro package to produce a
       formatted reference for each citation.  The output of refer must
       therefore be processed using a suitable macro package, such as ms,
       man, me, or mm.  The commands to format a citation's reference can be
       output immediately after the citation, or the references may be
       accumulated, and the commands output at some later point.  If the
       references are accumulated, then multiple citations of the same
       reference will produce a single formatted reference.

       The interpretation of lines between .R1 and .R2 as commands is a new
       feature of GNU refer.  Documents making use of this feature can still
       be processed by Unix refer just by adding the lines

              .de R1
              .ig R2
       to the beginning of the document.  This will cause troff to ignore
       everything between .R1 and .R2.  The effect of some commands can also
       be achieved by options.  These options are supported mainly for
       compatibility with Unix refer.  It is usually more convenient to use

       refer generates .lf lines so that filenames and line numbers in
       messages produced by commands that read refer output will be correct;
       it also interprets lines beginning with .lf so that filenames and
       line numbers in the messages and .lf lines that it produces will be
       accurate even if the input has been preprocessed by a command such as

Options         top

       Whitespace is permitted between a command-line option and its

       Most options are equivalent to commands (for a description of these
       commands, see subsection “Commands” below).

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

       -e     accumulate

       -n     no-default-database

       -C     compatible

       -P     move-punctuation

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

       -an    reverse An

              capitalize fields

       -fn    label %n

              search-ignore fields

       -k     label L~%a

              label field~%a

       -l     label A.nD.y%a

       -lm    label A.n+mD.y%a

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

       -lm,n  label A.n+mD.y-n%a

              database filename

       -sspec sort spec

       -tn    search-truncate n

       These options are equivalent to the following commands with the
       addition that the filenames 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

              annotate field macro; no-label-in-reference

       The following options have no equivalent commands:

       -v     Print the version number.

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

Usage         top

   Bibliographic databases
       The bibliographic database is a text file consisting of records
       separated by one or more blank lines.  Within each record fields
       start with a % at the beginning of a line.  Each field has a one
       character name that immediately follows the %.  It is best to use
       only upper and lower case letters for the names of fields.  The name
       of the field should be followed by exactly one space, and then by the
       contents of the field.  Empty fields are ignored.  The conventional
       meaning of each field is as follows:

       %A     The name of an author.  If the name contains a title such as
              Jr. at the end, it should be separated from the last name by a
              comma.  There can be multiple occurrences of the %A field.
              The order is significant.  It is a good idea always to supply
              an %A field or a %Q field.

       %B     For an article that is part of a book, the title of the book.

       %C     The place (city) of publication.

       %D     The date of publication.  The year should be specified in
              full.  If the month is specified, the name rather than the
              number of the month should be used, but only the first three
              letters are required.  It is a good idea always to supply a %D
              field; if the date is unknown, a value such as in press or
              unknown can be used.

       %E     For an article that is part of a book, the name of an editor
              of the book.  Where the work has editors and no authors, the
              names of the editors should be given as %A fields and , (ed)
              or , (eds) should be appended to the last author.

       %G     US Government ordering number.

       %I     The publisher (issuer).

       %J     For an article in a journal, the name of the journal.

       %K     Keywords to be used for searching.

       %L     Label.

       %N     Journal issue number.

       %O     Other information.  This is usually printed at the end of the

       %P     Page number.  A range of pages can be specified as m-n.

       %Q     The name of the author, if the author is not a person.  This
              will only be used if there are no %A fields.  There can only
              be one %Q field.

       %R     Technical report number.

       %S     Series name.

       %T     Title.  For an article in a book or journal, this should be
              the title of the article.

       %V     Volume number of the journal or book.

       %X     Annotation.

       For all fields except %A and %E, if there is more than one occurrence
       of a particular field in a record, only the last such field will be

       If accent strings are used, they should follow the character to be
       accented.  This means that the AM macro must be used with the -ms
       macros.  Accent strings should not be quoted: use one \ rather than

       The format of a citation is
              flags keywords

       The opening-text, closing-text, and flags components are optional.
       Only one of the keywords and fields components need be specified.

       The keywords component says to search the bibliographic databases for
       a reference that contains all the words in keywords.  It is an error
       if more than one reference if found.

       The fields components specifies additional fields to replace or
       supplement those specified in the reference.  When references are
       being accumulated and the keywords component is non-empty, then
       additional fields should be specified only on the first occasion that
       a particular reference is cited, and will apply to all citations of
       that reference.

       The opening-text and closing-text component specifies strings to be
       used to bracket the label instead of the strings specified in the
       bracket-label command.  If either of these components is non-empty,
       the strings specified in the bracket-label command will not be used;
       this behaviour can be altered using the [ and ] flags.  Note that
       leading and trailing spaces are significant for these components.

       The flags component is a list of non-alphanumeric characters each of
       which modifies the treatment of this particular citation.  Unix refer
       will treat these flags as part of the keywords and so will ignore
       them since they are non-alphanumeric.  The following flags are
       currently recognized:

       #      This says to use the label specified by the short-label
              command, instead of that specified by the label command.  If
              no short label has been specified, the normal label will be
              used.  Typically the short label is used with author-date
              labels and consists of only the date and possibly a
              disambiguating letter; the # is supposed to be suggestive of a
              numeric type of label.

       [      Precede opening-text with the first string specified in the
              bracket-label command.

       ]      Follow closing-text with the second string specified in the
              bracket-label command.

       One advantages of using the [ and ] flags rather than including the
       brackets in opening-text and closing-text is that you can change the
       style of bracket used in the document just by changing the bracket-
       label command.  Another advantage is that sorting and merging of
       citations will not necessarily be inhibited if the flags are used.

       If a label is to be inserted into the text, it will be attached to
       the line preceding the .[ line.  If there is no such line, then an
       extra line will be inserted before the .[ line and a warning will be

       There is no special notation for making a citation to multiple
       references.  Just use a sequence of citations, one for each
       reference.  Don't put anything between the citations.  The labels for
       all the citations will be attached to the line preceding the first
       citation.  The labels may also be sorted or merged.  See the
       description of the <> label expression, and of the sort-adjacent-
       labels and abbreviate-label-ranges command.  A label will not be
       merged if its citation has a non-empty opening-text or closing-text.
       However, the labels for a citation using the ] flag and without any
       closing-text immediately followed by a citation using the [ flag and
       without any opening-text may be sorted and merged even though the
       first citation's opening-text or the second citation's closing-text
       is non-empty.  (If you wish to prevent this just make the first
       citation's closing-text \&.)

       Commands are contained between lines starting with .R1 and .R2.
       Recognition of these lines can be prevented by the -R option.  When a
       .R1 line is recognized any accumulated references are flushed out.
       Neither .R1 nor .R2 lines, nor anything between them is output.

       Commands are separated by newlines or ;s.  # 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 " extends to the next "
       that is not followed by another ".  If there is no such " the word
       extends to the end of the line.  Pairs of " in a word beginning with
       " collapse to a single ".  Neither # nor ; are recognized inside "s.
       A line can be continued by ending it with \; this works everywhere
       except after a #.

       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;
       filename 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
              last name by string2, and from anything else (such as a 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 references instead of writing out each reference as
              it is encountered.  Accumulated references will be written out
              whenever a reference of the form


              is encountered, after all input files have been processed, and
              whenever .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


              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

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

       bibliography filename...
              Write out all the references contained in the bibliographic
              databases filename...  This command should come last in a
              .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 behaviour is

                     bracket-label \*([. \*(.] ", "

       capitalize fields
              Convert fields to caps and small caps.

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

       database filename...
              Search the bibliographic databases filename...  For each
              filename if an index filename.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.

              The default database should be searched.  This is the default
              behaviour, 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
              Control use of et al in the evaluation of @ expressions in
              label expressions.  If the number of authors needed to make
              the author sequence unambiguous is u 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 behaviour is

                     et-al " et al" 2 3

       include filename
              Include filename and interpret the contents as commands.

       join-authors string1 string2 string3
              This says how authors should be joined together.  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.

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

              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 behaviour; so the
              negative version of this command is more useful.

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

       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.

              In the text, move any punctuation at the end of line past the
              label.  It is usually a good idea to give this command unless
              you are using superscripted numbers as labels.

       reverse* string
              Reverse the fields whose names are in string.  Each field name
              can be followed by a number which says how many such fields
              should be reversed.  If no number is given for a field, all
              such fields will be reversed.

       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

              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 will have no effect unless references are being

   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
              The n-th part of field.  If n is omitted, it defaults to 1.

              The characters in string literally.

       @      All the authors joined as specified by the join-authors
              command.  The whole of each author's name will be used.
              However, if the references are sorted by author (that is the
              sort specification starts with A+), then authors last names
              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.  The use of only the last name
              for the i-th author of some reference is considered to be
              ambiguous if there is some other reference, such that the
              first i-1 authors of the references are the same, the i-th
              authors are not the same, but the i-th authors last names 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
              purpose will have the same representation.

       %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 The first (+) or last (-) n upper or lower case letters or
              digits of expr.  Troff 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 last name is first.

       expr.a expr with first names abbreviated.  Note that 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.

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

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

       expr.n The last name part of expr.

              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.

              If expr1 is non-empty then expr1 otherwise expr2.

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

              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.  Note that it is
              permissible for the first part to be empty; this maybe
              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 number register [P is set to 1 if the P
       field contains a range of pages.  The [T, [A and [O number registers
       are set to 1 according as the T, A and O fields end with one of the
       characters .?!.  The [E number 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 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.

Environment         top

       REFER  If set, overrides the default database.

Files         top

              Default database.

       file.i Index files.

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

Bugs         top

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

See Also         top

       “Some Applications of Inverted Indexes on the UNIX System”,
              M. E. Lesk, Bell Laboratories, 1979.  A gratis version of this
              document from volume 2A of the Unix Programmer's Manual, 7th
              edition, describes an early implementation of refer and is
              available at the website of the late W. Richard Stevens 

       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 
       ⟨⟩.  If you have a bug report for
       this manual page, see ⟨⟩.  This
       page was obtained from the project's upstream Git repository
       ⟨⟩ on 2020-06-09.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-06-04.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to

groff            16 May 2020                        refer(1)

Pages that refer to this page: groff(1)indxbib(1)lkbib(1)lookbib(1)groff_man(7)groff_me(7)groff_ms(7)