refer(1) General Commands Manual refer(1)
Name
refer - process bibliographic references for groff
Synopsis
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
Description
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 article.
%V Volume number of the journal or book.
%X Annotation.
For all fields except %A and %E, if there is more than one occurrence
of a particular field in a record, only the last such field will be
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
Citations have a characteristic format.
.[opening-text
flags keywords
fields
.]closing-text
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
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 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*
Accumulate references instead of writing out each reference as
it is encountered. Accumulated references will be written out
whenever a reference of the form
.[
$LIST$
.]
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
.string
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.
compatible*
Recognize .R1 and .R2 even when followed by a character other
than space or newline.
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 reference.
default-database*
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.
label-in-reference*
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 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 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.
move-punctuation*
In the text, move any punctuation at the end of line past the
label. It is usually a good idea to give this command unless
you are using superscripted numbers as labels.
reverse* string
Reverse the fields whose names are in string. Each field name
can be followed by a number which says how many such fields
should be reversed. If no number is given for a field, all such
fields will be reversed.
search-ignore* fields
While searching for keys in databases for which no index exists,
ignore the contents of fields. Initially, fields XYZ are
ignored.
search-truncate* n
Only require the first n characters of keys to be given. In
effect when searching for a given key words in the database are
truncated to the maximum of n and the length of the key.
Initially, n is 6.
short-label* string
string is a label expression that specifies an alternative
(usually shorter) style of label. This is used when the # flag
is given in the citation. When using author-date style labels,
the identity of the author or authors is sometimes clear from
the context, and so it may be desirable to omit the author or
authors from the label. The short-label command will typically
be used to specify a label containing just a date and possibly a
disambiguating letter.
sort* string
Sort references according to string. References will
automatically be accumulated. string should be a list of field
names, each followed by a number, indicating how many fields
with the name should be used for sorting. "+" can be used to
indicate that all the fields with the name should be used. Also
. can be used to indicate the references should be sorted using
the (tentative) label. (Subsection "Label expressions" below
describes the concept of a tentative label.)
sort-adjacent-labels*
Sort labels that are adjacent in the text according to their
position in the reference list. This command should usually be
given if the abbreviate-label-ranges command has been given, or
if the label expression contains a <> expression. This will
have no effect unless references are being accumulated.
Label expressions
Label expressions can be evaluated both normally and tentatively. The
result of normal evaluation is used for output. The result of
tentative evaluation, called the tentative label, is used to gather the
information that normal evaluation needs to disambiguate the label.
Label expressions specified by the date-as-label and short-label
commands are not evaluated tentatively. Normal and tentative
evaluation are the same for all types of expression other than @, *,
and % expressions. The description below applies to normal evaluation,
except where otherwise specified.
field
field n
The n-th part of field. If n is omitted, it defaults to 1.
'string'
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.
%n
%a
%A
%i
%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
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.
expr.+y
The part of expr before the year, or the whole of expr if it
does not contain a year.
expr.-y
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~expr2
expr1 except that if the last character of expr1 is - then it
will be replaced by expr2.
expr1 expr2
The concatenation of expr1 and expr2.
expr1|expr2
If expr1 is non-empty then expr1 otherwise expr2.
expr1&expr2
If expr1 is non-empty then expr2 otherwise an empty string.
expr1?expr2:expr3
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.
Options
--help displays a usage message, while -v and --version show version
information; all exit afterward.
-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
Environment
REFER If set, overrides the default database.
Files
/usr/dict/papers/Ind
Default database.
file.i Index files.
/opt/local/share/groff/1.23.0/tmac/refer.tmac
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 created.
Bugs
In label expressions, <> expressions are ignored inside .char
expressions.
Examples
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
.[
friedman
.]
on your summer vacation.
<Control+D>
.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
.LP
Read the book
.[
friedman
.]
on your summer vacation.
Commentary is available.\*{*\*}
.FS \*{*\*}
Space reserved for penetrating insight.
.FE
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 aside.
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)
groff 1.23.0 2 July 2023 refer(1)
groff 1.23.0 - Generated Sat Dec 23 06:20:35 CST 2023