Provided by: groff_1.23.0-2_amd64 bug


       refer - process bibliographic references for groff


       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


       The GNU implementation of refer is part of the groff(1) document formatting system.  refer
       is  a  troff(1)  preprocessor that prepares bibilographic 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.
       Normally,  refer  is  not  executed directly by the user, but invoked by specifying the -R
       option to groff(1).  If no file operands are given on the command line, or if file is “-”,
       the standard input stream is read.

       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(7) language 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 me, mm, mom, or  ms.   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 prepreocessor commands is a feature  of
       GNU refer.  Documents making use of this feature can still be processed by AT&T refer just
       by adding the lines
              .de R1
              .ig R2
       to the beginning of the document.  This will cause troff(1) 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 AT&T refer.  It is usually more convenient  to
       use commands.

       refer  generates  .lf requests so that file names and line numbers in messages produced by
       commands that read refer output will be correct; it also interprets lines  beginning  with
       .lf  so  that  file  names 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).

   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 suffix such as “Jr.”, 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     U.S. 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 reference.

       %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

       %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 used.

       If accent strings are used, they should follow the character to be accented.   This  means
       that  an  ms  document must call the .AM macro when it initializes.  Accent strings should
       not be quoted: use one \ rather than two.  Accent strings are an  obsolescent  feature  of
       the  me  and ms macro packages; modern documents should use groff special character escape
       sequences instead; see groff_char(7).

       Citations have a characteristic format.
              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 is 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  components specify strings to be used to bracket the
       label instead of those 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
       behavior can be altered using the  [  and  ]  flags.   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.  AT&T 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.

       #      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.

       An advantage 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 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 commands.  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, use the dummy character escape sequence \& as
       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

       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 last name 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 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 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


              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.

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

       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

              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
              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
              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.

              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

              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.

              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

       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 label.)

              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 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.   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 last name 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.

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

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

       expr.n The last name part of expr.

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

       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.  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.


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

       -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


       REFER  If set, overrides the default database.


              Default database.

       file.i Index files.

              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


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


       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
              on your summer vacation.
              .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
              Read the book
              on your summer vacation.
              Commentary is available.\*{*\*}
              .FS \*{*\*}
              Space reserved for penetrating insight.

       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

See also

       “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)