.TH \%refer 1 "16 October 2023" "groff 1.23.0"
.SH Name
\%refer \- process bibliographic references for
.I groff
.
.
.\" ====================================================================
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.\" ====================================================================
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.\" ====================================================================
.SH Synopsis
.\" ====================================================================
.
.SY \%refer
.RB [ \-bCenPRS ]
.RB [ \-a\~\c
.IR n ]
.RB [ \-B
.IB field . macro\c
]
.RB [ \-c\~\c
.IR fields ]
.RB [ \-f\~\c
.IR n ]
.RB [ \-i\~\c
.IR fields ]
.RB [ \-k\~\c
.IR field ]
.RB [ \-l\~\c
.IR range-expression ]
.RB [ \-p\~\c
.IR database-file ]
.RB [ \-s\~\c
.IR fields ]
.RB [ \-t\~\c
.IR n ]
.RI [ file\~ .\|.\|.]
.YS
.
.
.SY \%refer
.B \-\-help
.YS
.
.
.SY \%refer
.B \-v
.
.SY \%refer
.B \-\-version
.YS
.
.
.\" ====================================================================
.SH Description
.\" ====================================================================
.
The GNU implementation of
.I \%refer \" generic
is part of the
.MR groff 1
document formatting system.
.
.I \%refer
is a
.MR \%troff 1
preprocessor that prepares bibilographic citations by looking up
keywords specified in a
.MR 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
.I file
to the standard output stream,
except that it interprets lines between
.B .[
and
.B .]\&
as citations to be translated into
.I groff
input,
and lines between
.B .R1
and
.B .R2
as instructions regarding how citations are to be processed.
.
Normally,
.I \%refer
is not executed directly by the user,
but invoked by specifying the
.B \-R
option to
.MR groff 1 .
.
If no
.I file
operands are given on the command line,
or if
.I file
is
.RB \[lq] \- \[rq],
the standard input stream is read.
.
.
.LP
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.
.
.
.LP
For each citation,
.I \%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
.MR groff 7
language commands that can be used by a macro package to produce a
formatted reference for each citation.
.
The output of
.I \%refer
must therefore be processed using a suitable macro package,
such as
.\" .IR man ,
.IR me ,
.IR mm ,
.IR mom ,
or
.IR 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.
.
.
.LP
The interpretation of lines between
.B .R1
and
.B .R2
as prepreocessor commands is a feature of GNU
.IR \%refer . \" GNU
.
Documents making use of this feature can still be processed by AT&T
.I \%refer \" AT&T
just by adding the lines
.
.RS
.EX
\&.de R1
\&.ig R2
\&..
.EE
.RE
.
to the beginning of the document.
.
This will cause
.MR \%troff 1
to ignore everything between
.B .R1
and
.BR .R2 .
.
The effect of some commands can also be achieved by options.
.
These options are supported mainly for compatibility with AT&T
.IR \%refer . \" AT&T
.
It is usually more convenient to use commands.
.
.
.LP
.I \%refer
generates
.B .lf
requests so that file names and line numbers in messages produced by
commands that read
.I \%refer
output will be correct;
it also interprets lines beginning with
.B .lf
so that file names and line numbers in the messages and
.B .lf
lines that it produces will be accurate even if the input has been
preprocessed by a command such as
.MR \%soelim 1 .
.
.
.\" ====================================================================
.SS "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
.B %
at the beginning of a line.
.
Each field has a one character name that immediately follows the
.BR % .
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:
.
.
.TP
.B %A
The name of an author.
.
If the name contains a suffix such as \[lq]Jr.\&\[rq],
it should be separated from the last name by a comma.
.
There can be multiple occurrences of the
.B %A
field.
.
The order is significant.
.
It is a good idea always to supply an
.B %A
field or a
.B %Q
field.
.
.
.TP
.B %B
For an article that is part of a book,
the title of the book.
.
.
.TP
.B %C
The place (city) of publication.
.
.
.TP
.B %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
.B %D
field;
if the date is unknown,
a value such as
.B in press
or
.B unknown
can be used.
.
.
.TP
.B %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
.B %A
fields and
.RB \[lq] ,\~(ed.)\& \[rq]
or
.RB \[lq] ,\~(eds.)\& \[rq]
should be appended to the last author.
.
.
.TP
.B %G
U.S. government ordering number.
.
.
.TP
.B %I
The publisher (issuer).
.
.
.TP
.B %J
For an article in a journal,
the name of the journal.
.
.
.TP
.B %K
Keywords to be used for searching.
.
.
.TP
.B %L
Label.
.
.
.TP
.B %N
Journal issue number.
.
.
.TP
.B %O
Other information.
.
This is usually printed at the end of the reference.
.
.
.TP
.B %P
Page number.
.
A range of pages can be specified as
.IB m \- \c
.IR n .
.
.
.TP
.B %Q
The name of the author,
if the author is not a person.
.
This will only be used if there are no
.B %A
fields.
.
There can only be one
.B %Q
field.
.
.
.TP
.B %R
Technical report number.
.
.
.TP
.B %S
Series name.
.
.
.TP
.B %T
Title.
.
For an article in a book or journal,
this should be the title of the article.
.
.
.TP
.B %V
Volume number of the journal or book.
.
.
.TP
.B %X
Annotation.
.
.
.LP
For all fields except
.B %A
and
.BR %E ,
if there is more than one occurrence of a particular field in a record,
only the last such field will be used.
.
.
.P
If accent strings are used,
they should follow the character to be accented.
.
This means that an
.I ms
document must call the
.B .AM
macro when it initializes.
.
Accent strings should not be quoted:
use one
.B \e
rather than two.
.
Accent strings are an obsolescent feature of the
.I me
and
.I ms
macro packages;
modern documents should use
.I groff
special character escape sequences instead;
see
.MR groff_char 7 .
.
.
.\" ====================================================================
.SS Citations
.\" ====================================================================
.
Citations have a characteristic format.
.
.RS
.EX
.BI .[ opening-text
.I flags keywords
.I fields
.BI .] closing-text
.EE
.RE
.
.
.LP
The
.IR opening-text ,
.IR closing-text ,
and
.I flags
components are optional.
.
Only one of the
.I keywords
and
.I fields
components need be specified.
.
.
.LP
The
.I keywords
component says to search the bibliographic databases for a reference
that contains all the words in
.IR keywords .
.
It is an error if more than one reference is found.
.
.
.LP
The
.I fields
components specifies additional fields to replace or supplement those
specified in the reference.
.
When references are being accumulated and the
.I 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.
.
.
.br
.ne 2v
.LP
The
.I opening-text
and
.I closing-text
components specify strings to be used to bracket the label instead of
those in the
.B \%bracket\-label
command.
.
If either of these components is non-empty,
the strings specified in the
.B \%bracket\-label
command will not be used;
this behavior can be altered using the
.B [
and
.B ]
flags.
.
Leading and trailing spaces are significant for these components.
.
.
.LP
The
.I flags
component is a list of non-alphanumeric characters each of which
modifies the treatment of this particular citation.
.
AT&T
.I \%refer \" AT&T
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.
.
.
.TP
.B #
Use the label specified by the
.B \%short\-label
command,
instead of that specified by the
.B \%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
.RB \[lq] # \[rq]
is supposed to be suggestive of a numeric type of label.
.
.
.TP
.B [
Precede
.I opening-text
with the first string specified in the
.B \%bracket\-label
command.
.
.
.TP
.B ]
Follow
.I closing-text
with the second string specified in the
.B \%bracket\-label
command.
.
.
.LP
An advantage of using the
.B [
and
.B ]
flags rather than including the brackets in
.I opening-text
and
.I closing-text
is that
.
you can change the style of bracket used in the document just by
changing the
.B \%bracket\-label
command.
.
Another is that sorting and merging of citations will not necessarily be
inhibited if the flags are used.
.
.
.LP
If a label is to be inserted into the text,
it will be attached to the line preceding the
.B .[
line.
.
If there is no such line,
then an extra line will be inserted before the
.B .[
line and a warning will be given.
.
.
.LP
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
.B <>
label expression,
and of the
.B \%sort\-adjacent\-labels
and
.B \%abbreviate\-label\-ranges
commands.
.
A label will not be merged if its citation has a non-empty
.I opening-text
or
.IR closing-text .
.
However,
the labels for a citation using the
.B ]
flag and without any
.I closing-text
immediately followed by a citation using the
.B [
flag and without any
.I opening-text
may be sorted and merged
even though the first citation's
.I opening-text
or the second citation's
.I closing-text
is non-empty.
.
(If you wish to prevent this,
use the dummy character escape sequence
.B \[rs]&
as the first citation's
.IR closing-text .)
.
.
.\" ====================================================================
.SS Commands
.\" ====================================================================
.
Commands are contained between lines starting with
.B .R1
and
.BR .R2 .
.
Recognition of these lines can be prevented by the
.B \-R
option.
.
When a
.B .R1
line is recognized any accumulated references are flushed out.
.
Neither
.B .R1
nor
.B .R2
lines,
nor anything between them,
is output.
.
.
.P
Commands are separated by newlines or semicolons.
.
A number sign
.RB ( # )
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
.RB ( \[dq] )
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
.RB \[lq] \[rs] \[rq];
this works everywhere except after a number sign.
.
.
.LP
.ds n \fR*\fP\"
Each command
.I name
that is marked with \*n has an associated negative command
.BI no\- name
that undoes the effect of
.IR name .
.
For example,
the
.B no\-sort
command specifies that references should not be sorted.
.
The negative commands take no arguments.
.
.
.LP
In the following description each argument must be a single word;
.I field
is used for a single upper or lower case letter naming a field;
.I fields
is used for a sequence of such letters;
.I m
and
.I n
are used for a non-negative numbers;
.I string
is used for an arbitrary string;
.I file
is used for the name of a file.
.
.
.TP
.BI abbreviate\*n\~ fields\~string1\~string2\~string3\~string4
Abbreviate the first names of
.IR fields .
.
An initial letter will be separated from another initial letter by
.IR string1 ,
from the last name by
.IR string2 ,
and from anything else
(such as \[lq]von\[rq] or \[lq]de\[rq])
by
.IR 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
.IR 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.
.
.
.TP
.BI abbreviate\-label\-ranges\*n\~ string
.
Three or more adjacent labels that refer to consecutive references
will be abbreviated to a label consisting of the first label,
followed by
.IR string ,
followed by the last label.
.
This is mainly useful with numeric labels.
.
If
.I string
is omitted,
it defaults to
.RB \[lq] \- \[rq].
.
.
.TP
.B accumulate\*n
Accumulate references instead of writing out each reference
as it is encountered.
.
Accumulated references will be written out whenever a reference
of the form
.
.RS
.RS
.EX
.B .[
.B $LIST$
.B .]
.EE
.RE
.
is encountered,
after all input files have been processed,
and whenever a
.B .R1
line is recognized.
.RE
.
.
.TP
.BI annotate\*n\~ "field string"
.I field
is an annotation;
print it at the end of the reference as a paragraph preceded by the line
.
.RS
.IP
.BI . string
.
.
.LP
If
.I string
is omitted,
it will default to
.BR AP ;
if
.I field
is also omitted it will default to
.BR X .
.
Only one field can be an annotation.
.RE
.
.
.TP
.BI articles\~ string\~\c
\&.\|.\|.
Each
.I string
is a definite or indefinite article,
and should be ignored at the beginning of
.B T
fields when sorting.
.
Initially,
\[lq]a\[rq],
\[lq]an\[rq],
and
\[lq]the\[rq] are recognized as articles.
.
.
.TP
.BI bibliography\~ file\~\c
\&.\|.\|.
.
Write out all the references contained in each bibliographic database
.IR file .
.
This command should come last in an
.BR .R1 / .R2
block.
.
.
.TP
.BI bracket\-label\~ "string1 string2 string3"
In the text,
bracket each label with
.I string1
and
.IR string2 .
.
An occurrence of
.I string2
immediately followed by
.I string1
will be turned into
.IR string3 .
.
The default behavior is as follows.
.
.RS \" RS twice to get inboard of the tagged paragraph indentation.
.RS
.EX
.B bracket\-label \e*([. \e*(.] \[dq], \[dq]
.EE
.RE
.RE
.
.
.TP
.BI capitalize\~ fields
Convert
.I fields
to caps and small caps.
.
.
.TP
.B compatible\*n
Recognize
.B .R1
and
.B .R2
even when followed by a character other than space or newline.
.
.
.TP
.BI database\~ file\~\c
\&.\|.\|.
Search each bibliographic database
.IR file .
.
For each
.IR file ,
if an index
.RI file \%.i
created by
.MR \%indxbib 1
exists,
then it will be searched instead;
each index can cover multiple databases.
.
.
.TP
.BI date\-as\-label\*n\~ string
.I string
is a label expression that specifies a string with which to replace the
.B D
field after constructing the label.
.
See subsection \[lq]Label expressions\[rq] 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
.B \%no\-label\-in\-reference
command.
.
For example,
.
.RS \" RS twice to get inboard of the tagged paragraph indentation.
.RS
.EX
.B date\-as\-label D.+yD.y%a*D.\-y
.EE
.RE
.
would attach a disambiguating letter to the year part of the
.B D
field in the reference.
.RE
.
.
.TP
.B default\-database\*n
The default database should be searched.
.
This is the default behavior,
so the negative version of this command is more useful.
.
.I \%refer
determines whether the default database should be searched
on the first occasion that it needs to do a search.
.
Thus a
.B \%no\-default\-database
command must be given before then,
in order to be effective.
.
.
.TP
.BI discard\*n\~ fields
When the reference is read,
.I fields
should be discarded;
no string definitions for
.I fields
will be output.
.
Initially,
.I fields
are
.BR XYZ .
.
.
.TP
.BI et\-al\*n\~ "string m n"
Control use of
.B et al.\&
in the evaluation of
.B @
expressions in label expressions.
.
If the number of authors needed to make the author sequence unambiguous
is
.I u
and the total number of authors is
.I t
then the last
.IR t \|\-\| u
authors will be replaced by
.I string
provided that
.IR t \|\-\| u
is not less than
.I m
and
.I t
is not less than
.IR n .
.
The default behavior is as follows.
.
.RS \" RS twice to get inboard of the tagged paragraph indentation.
.RS
.EX
.B et\-al \[dq] et al\[dq] 2 3
.EE
.RE
.
Note the absence of a dot from the end of the abbreviation,
which is arguably not correct.
.
.RI ( "Et al" [.]
is short for
.IR "et alli" ,
as
.I etc.\&
is short for
.IR "et cetera".)
.RE
.
.
.TP
.BI include\~ file
Include
.I file
and interpret the contents as commands.
.
.
.TP
.BI join\-authors\~ "string1 string2 string3"
Join multiple authors together with
.IR string s.
.
When there are exactly two authors,
they will be joined with
.IR string1 .
.
When there are more than two authors,
all but the last two will be joined with
.IR string2 ,
and the last two authors will be joined with
.IR string3 .
.
If
.I string3
is omitted,
it will default to
.IR string1 ;
if
.I string2
is also omitted it will also default to
.IR string1 .
.
For example,
.
.RS
.RS
.EX
join\-authors \[dq] and \[dq] \[dq], \[dq] \[dq], and \[dq]
.EE
.RE
.
will restore the default method for joining authors.
.RE
.
.
.TP
.B label\-in\-reference\*n
When outputting the reference,
define the string
.B [F
to be the reference's label.
.
This is the default behavior,
so the negative version of this command is more useful.
.
.
.TP
.B label\-in\-text\*n
For each reference output a label in the text.
.
The label will be separated from the surrounding text as described in
the
.B \%bracket\-label
command.
.
This is the default behavior,
so the negative version of this command is more useful.
.
.
.TP
.BI label\~ string
.I string
is a label expression describing how to label each reference.
.
.
.TP
.BI separate\-label\-second\-parts\~ string
When merging two-part labels,
separate the second part of the second label from the first label with
.IR string .
.
See the description of the
.B <>
label expression.
.
.
.TP
.B move\-punctuation\*n
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.
.
.
.TP
.BI reverse\*n\~ string
Reverse the fields whose names
are in
.IR 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.
.
.
.TP
.BI search\-ignore\*n\~ fields
While searching for keys in databases for which no index exists,
ignore the contents of
.IR fields .
.
Initially,
fields
.B XYZ
are ignored.
.
.
.TP
.BI search\-truncate\*n\~ n
Only require the first
.I 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
.I n
and the length of the key.
.
Initially,
.I n
is\~6.
.
.
.TP
.BI short\-label\*n\~ string
.I string
is a label expression that specifies an alternative
(usually shorter)
style of label.
.
This is used when the
.B #
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
.B \%short\-label
command will typically be used to specify a label containing just
a date and possibly a disambiguating letter.
.
.
.TP
.BI sort\*n\~ string
Sort references according to
.IR string .
.
References will automatically be accumulated.
.
.I 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.
.
.RB \[lq] + \[rq]
can be used to indicate that all the fields with the name should be
used.
.
Also
.B .\&
can be used to indicate the references should be sorted using the
(tentative) label.
.
(Subsection \[lq]Label expressions\[rq] below describes the concept of a
tentative label.)
.
.
.TP
.B sort\-adjacent\-labels\*n
Sort labels that are adjacent in the text according to their position
in the reference list.
.
This command should usually be given if the
.B \%abbreviate\-label\-ranges
command has been given,
or if the label expression contains a
.B <>
expression.
.
This will have no effect unless references are being accumulated.
.
.
.\" ====================================================================
.SS "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
.IR "tentative label" ,
is used to gather the information that normal evaluation needs to
disambiguate the label.
.
Label expressions specified by the
.B \%date\-as\-label
and
.B \%short\-label
commands are not evaluated tentatively.
.
Normal and tentative evaluation are the same for all types of expression
other than
.BR @ ,
.BR * ,
and
.B %
expressions.
.
The description below applies to normal evaluation,
except where otherwise specified.
.
.
.TP
.I field
.TQ
.I field\~n
The
.IR n -th
part of
.IR field .
.
If
.I n
is omitted,
it defaults to\~1.
.
.
.TP
.BI \[aq] string \[aq]
The characters in
.I string
literally.
.
.
.TP
.B @
All the authors joined as specified by the
.B \%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
.RB \[lq] A+ \[rq]),
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
.IR i -th
author of some reference
is considered to be ambiguous if
there is some other reference,
such that the first
.IR i \|\-\|1
authors of the references are the same,
the
.IR i -th
authors are not the same,
but the
.IR 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
.B \%et\-al
command;
this command may also specify additional requirements that must be
met before an initial subsequence can be used.
.
.B @
tentatively evaluates to a canonical representation of the authors,
such that authors that compare equally for sorting purpose will have
the same representation.
.
.
.TP
.BI % n
.TQ
.B %a
.TQ
.B %A
.TQ
.B %i
.TQ
.B %I
The serial number of the reference formatted according to the
character following the
.BR % .
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.
.
.TP
.IB expr *
If there is another reference with the same tentative label as this
reference,
then
.IR expr ,
otherwise an empty string.
.
It tentatively evaluates to an empty string.
.
.
.TP
.IB expr + n
.TQ
.IB expr \- n
The first
.RB ( + )
or last
.RB ( \- )
.I n
upper or lower case letters or digits of
.IR expr .
.
.I roff
special characters
(such as
.BR \e(\[aq]a )
count as a single letter.
.
Accent strings are retained but do not count towards the total.
.
.
.TP
.IB expr .l
.I expr
converted to lowercase.
.
.
.TP
.IB expr .u
.I expr
converted to uppercase.
.
.
.TP
.IB expr .c
.I expr
converted to caps and small caps.
.
.
.TP
.IB expr .r
.I expr
reversed so that the last name is first.
.
.
.TP
.IB expr .a
.I expr
with first names abbreviated.
.
Fields specified in the
.B \%abbreviate
command are abbreviated before any labels are evaluated.
.
Thus
.B .a
is useful only when you want a field to be abbreviated in a label
but not in a reference.
.
.
.TP
.IB expr .y
The year part of
.IR expr .
.
.
.TP
.IB expr .+y
The part of
.I expr
before the year,
or the whole of
.I expr
if it does not contain a year.
.
.
.TP
.IB expr .\-y
The part of
.I expr
after the year,
or an empty string if
.I expr
does not contain a year.
.
.
.TP
.IB expr .n
The last name part of
.IR expr .
.
.
.TP
.IB expr1 \[ti] expr2
.I expr1
except that if the last character of
.I expr1
is
.B \-
then it will be replaced by
.IR expr2 .
.
.
.TP
.I expr1 expr2
The concatenation of
.I expr1
and
.IR expr2 .
.
.
.TP
.IB expr1 | expr2
If
.I expr1
is non-empty then
.I expr1
otherwise
.IR expr2 .
.
.
.TP
.IB expr1 & expr2
If
.I expr1
is non-empty
then
.I expr2
otherwise an empty string.
.
.
.TP
.IB expr1 ? expr2 : expr3
If
.I expr1
is non-empty
then
.I expr2
otherwise
.IR expr3 .
.
.
.TP
.BI < expr >
The label is in two parts,
which are separated by
.IR 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
.B \%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
.B \%short\-label
command.
.
.
.TP
.BI ( expr )
The same as
.IR expr .
.
Used for grouping.
.
.
.LP
The above expressions are listed in order of precedence
(highest first);
.B &
and
.B |
have the same precedence.
.
.
.\" ====================================================================
.SS "Macro interface"
.\" ====================================================================
.
Each reference starts with a call to the macro
.BR ]\- .
.
The string
.B [F
will be defined to be the label for this reference,
unless the
.B \%no\-label\-in\-reference
command has been given.
.
There then follows a series of string definitions,
one for each field:
string
.BI [ X
corresponds to field
.IR X .
.
The register
.B [P
is set to\~1 if the
.B P
field contains a range of pages.
.
The
.BR [T ,
.B [A
and
.B [O
registers are set to\~1 according as the
.BR T ,
.B A
and
.B O
fields end with any of
.B .?!\&
(an end-of-sentence character).
.
The
.B [E
register will be set to\~1 if the
.B [E
string contains more than one name.
.
The reference is followed by a call to the
.B ][
macro.
.
The first argument to this macro gives a number representing
the type of the reference.
.
If a reference contains a
.B J
field,
it will be classified as type\~1,
otherwise if it contains a
.B B
field,
it will be type\~3,
otherwise if it contains a
.B G
or
.B R
field it will be type\~4,
otherwise if it contains an
.B I
field it will be type\~2,
otherwise it will be type\~0.
.
The second argument is a symbolic name for the type:
.BR other ,
.BR \%journal\-article ,
.BR book ,
.BR \%article\-in\-book ,
or
.BR \%tech\-report .
.
Groups of references that have been accumulated or are produced by the
.B \%bibliography
command are preceded by a call to the
.B ]<
macro and followed by a call to the
.B ]>
macro.
.
.
.br
.ne 4v
.\" ====================================================================
.SH Options
.\" ====================================================================
.
.B \-\-help
displays a usage message,
while
.B \-v
and
.B \-\-version
show version information;
all exit afterward.
.
.
.TP
.B \-R
Don't recognize lines beginning with
.BR .R1 / .R2 .
.
.
.P
Other options are equivalent to
.I \%refer
commands.
.
.
.TP 16n
.BI \-a\~ n
.B reverse
.BI A n
.
.
.TP
.B \-b
.B "\%no\-label\-in\-text; \%no\-label\-in\-reference"
.
.
.TP
.B \-B
See below.
.
.
.TP
.BI \-c\~ fields
.B capitalize
.I fields
.
.
.TP
.B \-C
.B compatible
.
.
.TP
.B \-e
.B accumulate
.
.
.TP
.BI \-f\~ n
.B \%label
.BI % n
.
.
.TP
.BI \-i\~ fields
.B search\-ignore
.I fields
.
.
.TP
.B \-k
.B \%label
.B L\[ti]%a
.
.
.TP
.BI \-k\~ field
.B \%label
.IB field \[ti]%a
.
.
.TP
.B \-l
.B \%label
.B A.nD.y%a
.
.
.TP
.BI \-l\~ m
.B \%label
.BI A.n+ m D.y%a
.
.
.TP
.BI \-l\~, n
.B \%label
.BI A.nD.y\- n %a
.
.
.TP
.BI \-l\~ m , n
.B \%label
.BI A.n+ m D.y\- n %a
.
.
.TP
.B \-n
.B \%no\-default\-database
.
.
.TP
.BI \-p\~ db-file
.B database
.I db-file
.
.
.TP
.B \-P
.B move\-punctuation
.
.
.TP
.BI \-s\~ spec
.B sort
.I spec
.
.
.TP
.B \-S
.B \%label \[dq](A.n|Q) \[aq], \[aq] (D.y|D)\[dq]; \
\%bracket-\%label \[dq]\~(\[dq]\~)\~\[dq];\~\[dq]
.
.
.TP
.BI \-t\~ n
.B search\-truncate
.I n
.
.
.P
The
.B 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
.B \%bibliography
command instead of in the normal way.
.
.
.TP 16n
.B \-B
.B "annotate X AP; \%no\-label\-in\-reference"
.
.
.TP
.BI \-B\~ field . macro
.B annotate
.I field
.IB macro ;
.B \%no\-label\-in\-reference
.
.
.\" ====================================================================
.SH Environment
.\" ====================================================================
.
.TP
.I REFER
If set,
overrides the default database.
.
.
.\" ====================================================================
.SH Files
.\" ====================================================================
.
.TP
.I /usr/\:\%dict/\:\%papers/\:\%Ind
Default database.
.
.
.TP
.RI file \%.i
Index files.
.
.
.TP
.I /usr/\:\%share/\:\%groff/\:\%1.23.0/\:\%tmac/\:refer\:.tmac
defines macros and strings facilitating integration with macro packages
that wish to support
.IR \%refer .
.
.
.LP
.I \%refer
uses temporary files.
.
See the
.MR groff 1
man page for details of where such files are created.
.
.
.\" ====================================================================
.SH Bugs
.\" ====================================================================
.
In label expressions,
.B <>
expressions are ignored inside
.BI . char
expressions.
.
.
.\" ====================================================================
.SH Examples
.\" ====================================================================
.
We can illustrate the operation of
.I \%refer
with a sample bibliographic database containing one entry and a simple
.I roff
document to cite that entry.
.
.
.P
.RS
.EX
$ \c
.B cat > my\-db\-file
.B %A Daniel P.\[rs]& Friedman
.B %A Matthias Felleisen
.B %C Cambridge, Massachusetts
.B %D 1996
.B %I The MIT Press
.B %T The Little Schemer, Fourth Edition
$ \c
.B refer -p my\-db\-file
.B Read the book
.B .[
.B friedman
.B .]
.B on your summer vacation.
.I <Control+D>
\&.lf 1 \-
Read the book\[rs]*([.1\[rs]*(.]
\&.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.
.EE
.RE
.
.
.P
The foregoing shows us that
.I \%refer
(a) produces a label \[lq]1\[rq];
(b) brackets that label with interpolations of the
.RB \[lq] [. \[rq]
and
.RB \[lq] .] \[rq]
strings;
(c) calls a macro
.RB \[lq] ]\- \[rq];
(d) defines strings and registers containing the label and bibliographic
data for the reference;
(e) calls a macro
.RB \[lq] ][ \[rq];
and (f) uses the
.B lf
request to restore the line numbers of the original input.
.
As discussed in subsection \[lq]Macro interface\[rq] 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
.MR groff_ms 7
to this task.
.
.
.P
.RS
.EX
$ \c
.B REFER=my\-db\-file groff \-R \-ms
.B .LP
.B Read the book
.B .[
.B friedman
.B .]
.B on your summer vacation.
.B Commentary is available.\[rs]*{*\[rs]*}
.B .FS \[rs]*{*\[rs]*}
.B Space reserved for penetrating insight.
.B .FE
.EE
.RE
.
.
.LP
.IR ms 's
automatic footnote numbering mechanism is not aware of
.IR \%refer 's
label numbering,
so we have manually specified a (superscripted) symbolic footnote for
our non-bibliographic aside.
.
.
.\" ====================================================================
.SH "See also"
.\" ====================================================================
.
\[lq]Some Applications of Inverted Indexes on the Unix System\[rq],
by M.\& E.\& Lesk,
1978,
AT&T Bell Laboratories Computing Science Technical Report No.\& 69.
.
.
.LP
.MR \%indxbib 1 ,
.MR \%lookbib 1 ,
.MR lkbib 1
.
.
.\" Restore compatibility mode (for, e.g., Solaris 10/11).
.cp \n[*groff_refer_1_man_C]
.do rr *groff_refer_1_man_C
.
.
.\" Local Variables:
.\" fill-column: 72
.\" mode: nroff
.\" End:
.\" vim: set filetype=groff textwidth=72: