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refer - preprocess bibliographic references for groff
refer [ -benvCPRS ] [ -an ] [ -cfields ] [ -fn ] [ -ifields ]
[ -kfield ] [ -lm,n ] [ -pfilename ] [ -sfields ] [ -tn ]
[ -Bfield.macro ] [ filename... ]
It is possible to have whitespace between a command line option and its
This file documents the GNU version of refer, which is part of the
groff document formatting system. refer copies the contents of file-
name... 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 refer-
ence that is contained in a bibliographic database by giving a set of
keywords that only that reference contains. Alternatively it can spec-
ify a reference by supplying a database record in the citation. A com-
bination 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 accumu-
lated, 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
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 compat-
ibility with Unix refer. It is usually more convenient to use com-
refer generates .lf lines so that filenames and line numbers in mes-
sages 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).
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
-S label "(A.n|Q) ', ' (D.y|D)"; bracket-label " (" ) "; "
-an reverse An
-fn label %n
-k label L~%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
-sspec sort spec
-tn search-truncate n
These options are equivalent to the following commands with the addi-
tion that the filenames specified on the command line are processed as
if they were arguments to the bibliography command instead of in the
-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.
The bibliographic database is a text file consisting of records sepa-
rated 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
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.
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.
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 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
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 supple-
ment those specified in the reference. When references are being accu-
mulated and the keywords component is non-empty, then additional fields
should be specified only on the first occasion that a particular refer-
ence 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. Typi-
cally the short label is used with author-date labels and con-
sists 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
] Follow closing-text with the second string specified in the
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 cita-
tions 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 refer-
ences. Just use a sequence of citations, one for each reference.
Don't put anything between the citations. The labels for all the cita-
tions 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. Recog-
nition 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 fol-
lowed 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 sin-
gle ". Neither # nor ; are recognized inside "s. A line can be con-
tinued by ending it with \; this works everywhere except after a #.
Each command name that is marked with * has an associated negative com-
mand 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-neg-
ative 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 ini-
tial 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
Three or more adjacent labels that refer to
consecutive references will be abbreviated to
a label consisting of the first label, fol-
lowed 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. Accumu-
lated 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 rec-
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 com-
mand 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 immedi-
ately 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 cre-
ated by indxbib(1) exists, then it will be
searched instead; each index can cover multi-
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 expres-
sions 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 typi-
cally be some combination of the author and
date. In most cases you should also use the
no-label-in-reference command. For example,
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 ver-
sion 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-data-
base 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 num-
ber 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 ver-
sion 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 surround-
ing text as described in the bracket-label
command. This is the default behaviour; so
the negative version of this command is more
label string string is a label expression describing how to
label each reference.
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 contain-
ing just a date and possibly a disambiguating
sort* string Sort references according to string. Refer-
ences 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 sort-
ing. * 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 can be evaluated both normally and tentatively. The
result of normal evaluation is used for output. The result of tenta-
tive 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 com-
mands are not evaluated tentatively. Normal and tentative evaluation
are the same for all types of expression other than @, *, and % expres-
sions. The description below applies to normal evaluation, except
where otherwise specified.
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 ambigu-
ity. 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 sub-
sequence. 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 require-
ments 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 tenta-
tively evaluates to an empty string.
expr-n The first (*) or last (-) n upper or lower case letters or dig-
its 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.
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.
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 num-
ber 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 ref-
erence. 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/share/dict/papers/Ind Default database.
file.i Index files.
REFER If set, overrides the default database.
indxbib(1), lookbib(1), lkbib(1)
In label expressions, <> expressions are ignored inside .char expres-
Groff Version 1.20.1 09 August 2013 REFER(1)