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 out-
put, except that lines between .[ and .] are interpreted
as citations, and lines between .R1 and .R2 are inter-
preted as commands about how citations are to be pro-
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 refer-
ence contains. Alternatively it can specify a reference
by supplying a database record in the citation. A combi-
nation 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 cita-
tion's reference can be output immediately after the cita-
tion, or the references may be accumulated, and the com-
mands 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 com-
mands 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 compatibility with Unix
refer. It is usually more convenient to use commands.
refer generates .lf lines so that filenames and line
Groff Version 1.15 9 April 2000 1
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 mes-
sages and .lf lines that it produces will be accurate even
if the input has been preprocessed by a command such as
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
Groff Version 1.15 9 April 2000 2
These options are equivalent to the following commands
with the addition that the filenames specified on the com-
mand 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.
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 fol-
lows 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 sepa-
rated 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
C The place (city) of publication.
D The date of publication. The year should be speci-
fied 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.
Groff Version 1.15 9 April 2000 3
G US Government ordering number.
I The publisher (issuer).
J For an article in a journal, the name of the jour-
K Keywords to be used for searching.
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
Q The name of the author, if the author is not a per-
son. 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 charac-
ter 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 two.
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.
Groff Version 1.15 9 April 2000 4
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
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
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 charac-
ters each of which modifies the treatment of this particu-
lar 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 rec-
# 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 speci-
fied, 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 disam-
biguating letter; the # is supposed to be sugges-
tive of a numeric type of label.
[ Precede opening-text with the first string speci-
fied in the bracket-label command.
] Follow closing-text with the second string speci-
fied 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 docu-
ment 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.
Groff Version 1.15 9 April 2000 5
There is no special notation for making a citation to mul-
tiple references. Just use a sequence of citations, one
for each reference. Don't put anything between the cita-
tions. 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 fol-
lowed by a citation using the [ flag and without any open-
ing-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 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 single ". Neither # nor ;
are recognized inside "s. A line can be continued by end-
ing 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 argu-
In the following description each argument must be a sin-
gle 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
Groff Version 1.15 9 April 2000 6
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 ini-
tial 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 con-
Three or more adjacent labels
that refer to consecutive refer-
ences will be abbreviated to a
label consisting of the first
label, followed by string fol-
lowed 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 ref-
erences will be written out when-
ever a reference of the form
is encountered, after all input
files hve 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 macro is omitted it will
default to AP; if field is also
omitted it will default to X.
Only one field can be an annota-
articles string... string... are definite or indef-
inite articles, and should be
ignored at the beginning of T
Groff Version 1.15 9 April 2000 7
fields when sorting. Initially,
the, a and an are recognized as
bibliography filename... Write out all the references con-
tained in the bibliographic
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
bracket-label \*([. \*(.]
capitalize fields Convert fields to caps and small
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
date-as-label* string string is a label expression that
specifies a string with which to
replace the D field after con-
structing the label. See the
Label expressions subsection for
a description of label expres-
sions. This command is useful if
you do not want explicit labels
in the reference list, but
instead want to handle any neces-
sary 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,
Groff Version 1.15 9 April 2000 8
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 use-
ful. 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 com-
mand 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 eval-
uation 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
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
Groff Version 1.15 9 April 2000 9
join-authors " and " ", "
", and "
will restore the default method
for joining authors.
label-in-reference* When outputting the reference,
define the string [F to be the
reference's label. This is the
default behaviour; so the nega-
tive version of this command is
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 nega-
tive version of this command is
label string string is a label expression
describing how to label each ref-
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
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
Groff Version 1.15 9 April 2000 10
search-truncate* n Only require the first n charac-
ters 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 some-
times 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
sort* string Sort references according to
string. References will automat-
ically be accumulated. string
should be a list of field names,
each followed by a number, indi-
cating 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 (ten-
tative) label. (The Label
expressions subsection describes
the concept of a tentative
sort-adjacent-labels* Sort labels that are adjacent in
the text according to their posi-
tion 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
Label expressions can be evaluated both normally and
Groff Version 1.15 9 April 2000 11
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 tenta-
tive evaluation are the same for all types of expression
other than @, *, and % expressions. The description below
applies to normal evaluation, except where otherwise spec-
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 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 addi-
tional requirements that must be met before an ini-
tial subsequence can be used. @ tentatively evalu-
ates 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
Groff Version 1.15 9 April 2000 12
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 tenta-
tive label as this reference, then expr, otherwise
an empty string. It tentatively evaluates to an
expr-n The first (+) or last (-) n upper or lower case
letters or digits of expr. Troff special charac-
ters (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.
Groff Version 1.15 9 April 2000 13
If expr1 is non-empty then expr2 otherwise an empty
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 sep-
arate-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 desir-
able for expressions used in the short-label com-
(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 refer-
ence, 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 con-
tains a G or R field it will be type 4, otherwise if con-
tains 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 accumu-
lated or are produced by the bibliography command are pre-
ceded by a call to the ]<< macro and followed by a call to
the ]>> macro.
/usr/share/dict/papers/Ind Default database.
Groff Version 1.15 9 April 2000 14
file.i Index files.
indxbib(1), lookbib(1), lkbib(1)
In label expressions, <<>> expressions are ignored inside
Groff Version 1.15 9 April 2000 15