refer - preprocess bibliographic references for groff


   refer [ -benvCPRS ] [ -an ] [ -cfields ] [ -fn ] [ -ifields ]
         [ -kfield ] [ -lm,n ] [ -pfilename ] [ -sfields ] [ -tn ]
         [ -Bfield.macro ] [ filename... ]


   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.  The -ms and -me  macros  are
   both  suitable.   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 soelim(1).


   It is possible to have whitespace between a command line option and its

   Most options are equivalent to commands (for  a  description  of  these
   commands see the Commands subsection):

   -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.


   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

   %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

   #      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 given.

   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

   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


                            is encountered, after  all  input  files  have
                            been  processed,  and  whenever  .R1  line  is

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


                            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...       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.

   compatible*              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  the  Label
                            expressions subsection 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  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

   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

   label-in-reference*      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.

   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 behaviour;
                            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.  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.
                            (The Label  expressions  subsection  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  will  have  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
          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

   %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 contains a 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.


   /usr/dict/papers/Ind  Default database.

   file.i                Index files.

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


   REFER  If set, overrides the default database.


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


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


   Copyright  1989-2014 Free Software Foundation, Inc.

   Permission is granted to make and distribute verbatim  copies  of  this
   manual  provided  the  copyright  notice and this permission notice are
   preserved on all copies.

   Permission is granted to copy and distribute modified versions of  this
   manual  under  the  conditions  for verbatim copying, provided that the
   entire resulting derived work is  distributed  under  the  terms  of  a
   permission notice identical to this one.

   Permission  is  granted  to  copy  and  distribute translations of this
   manual into another language, under the above conditions  for  modified
   versions,  except  that  this  permission  notice  may  be  included in
   translations approved by the Free Software Foundation instead of in the
   original English.


Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.

Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.

Free Software

Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.

Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.

Free Books

The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.

Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.


Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.

Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.