REFER(1) General Commands Manual REFER(1)
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 parameter.
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 inter-
preted 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 accu-
mulated, 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 compatibility with Unix refer. It is usually more convenient to use commands.
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).
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 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.
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
B For an article that is part of a book, the title of the book.
C The place (city) of publication.
D The date of publication. The year should be specified in full. If the month is specified, the name rather than the number of the
month should be used, but only the first three letters are required. It is a good idea always to supply a D field; if the date is
unknown, a value such as in press or unknown can be used.
E For an article that is part of a book, the name of an editor of the book. Where the work has editors and no authors, the names of
the editors should be given as A fields and , (ed) or , (eds) should be appended to the last author.
G US Government ordering number.
I The publisher (issuer).
J For an article in a journal, the name of the journal.
K Keywords to be used for searching.
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
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
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 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.
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 particu-
lar 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 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 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 cita-
tion 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 pre-
vent 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; file-
name is used for the name of a file.
abbreviate* fields string1 string2 string3 string4
Abbreviate the first names of fields. An initial letter will be separated from another initial letter by string1,
from the last name by string2, and from anything else (such as a von or de) by string3. These default to a period
followed by a space. In a hyphenated first name, the initial of the first part of the name will be separated from
the hyphen by string4; this defaults to a period. No attempt is made to handle any ambiguities that might result
from abbreviation. Names are abbreviated before sorting and before label construction.
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 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
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,
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. Ini-
tially, fields are XYZ.
et-al* string m n Control use of et al in the evaluation of @ expressions in label expressions. If the number of authors needed to
make the author sequence unambiguous is u and the total number of authors is t then the last t-u authors will be
replaced by string provided that t-u is not less than m and t is not less than n. The default behaviour is
et-al " et al" 2 3
include filename Include filename and interpret the contents as commands.
join-authors string1 string2 string3
This says how authors should be joined together. When there are exactly two authors, they will be joined with
string1. When there are more than two authors, all but the last two will be joined with string2, and the last two
authors will be joined with string3. If string3 is omitted, it will default to string1; if string2 is also omit-
ted it will also default to string1. For example,
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 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 use-
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 com-
mand 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
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 ref-
erences 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 ten-
tative 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.
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, pro-
vided 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 con-
sidered 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
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 sin-
gle 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 eval-
uated. 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-sec-
ond-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 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
/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 expressions.
Groff Version 1.19.2 February 6, 2006 REFER(1)