refer - Unix, Linux Command
refer - preprocess bibliographic references for groff
[ -benvCPRS ]
[ -a ]
[ -c ]
[ -f ]
[ -i ]
[ -k ]
[ -l ]
[ -p ]
[ -s ]
[ -t ]
[ -B ] [ filename... ]
It is possible to have whitespace between a command line option and its
This file documents the GNU version of
refer, which is part of the groff document formatting system.
refer copies the contents of
filename... to the standard output,
except that lines between
.] are interpreted as citations,
and lines between
.R2 are interpreted 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.
-me macros are both suitable.
The commands to format a citations reference can be output immediately after
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
.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
.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.
.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
Most options are equivalent to commands
(for a description of these commands see the
label "(A.n|Q) , (D.y|D)"; bracket-label " (" ) "; "
reverse An |
capitalize fields |
label %n |
search-ignore fields |
label L%a |
label field%a |
label A.nD.y%a |
label A.n+mD.y%a |
label A.nD.y-n%a |
label A.n+mD.y-n%a |
database filename |
sort spec |
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:
annotate X AP; no-label-in-reference
annotate field macro; no-label-in-reference |
The following options have no equivalent commands:
Print the version number.
Dont recognize lines beginning with
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
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:
For all fields except
E, if there is more than one occurrence of a particular field in a record,
only the last such field will be used.
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
The order is significant.
It is a good idea always to supply an
A field or a
For an article that is part of a book, the title of the book
The place (city) of publication.
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
if the date is unknown, a value such as
in press or
unknown can be used.
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.
US Government ordering number.
The publisher (issuer).
For an article in a journal, the name of the journal.
Keywords to be used for searching.
Journal issue number.
This is usually printed at the end of the reference.
A range of pages can be specified as
The name of the author, if the author is not a person.
This will only be used if there are no
There can only be one
Technical report number.
For an article in a book or journal,
this should be the title of the article.
Volume number of the journal or book.
If accent strings are used, they should follow the character to be accented.
This means that the
AM macro must be used with the
Accent strings should not be quoted:
\ rather than two.
The format of a citation is
opening-text, closing-text and
flags components are optional.
Only one of the
fields components need be specified.
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.
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.
closing-text component specifies strings to be used to bracket the label instead
of the strings specified in the
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
Note that leading and trailing spaces are significant for these components.
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 recognized:
One advantages of using the
] flags rather than including the brackets in
closing-text is that
you can change the style of bracket used in the document just by changing the
Another advantage is that sorting and merging of citations
will not necessarily be inhibited if the flags are used.
This says to use the label specified by the
instead of that specified by the
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;
# is supposed to be suggestive of a numeric type of label.
opening-text with the first string specified in the
closing-text with the second string specified in the
If a label is to be inserted into the text,
it will be attached to the line preceding the
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.
Dont 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
A label will not be merged if its citation has a non-empty
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 citations
opening-text or the second citations
closing-text is non-empty.
(If you wish to prevent this just make the first citations
Commands are contained between lines starting with
.R2. Recognition of these lines can be prevented by the
.R1 line is recognized any accumulated references are flushed out.
nor anything between them
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
s extends to the next
s that is not followed by another
s. If there is no such
s the word extends to the end of the line.
s in a word beginning with
s collapse to a single
; are recognized inside
ss. A line can be continued by ending it with
\; this works everywhere except after a
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;
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 anything else
(such as a
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
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.
string is omitted it defaults to
Accumulate references instead of writing out each reference
as it is encountered.
Accumulated references will be written out whenever a reference
of the form
after all input files hve been processed,
.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
macro is omitted it will default to
field is also omitted it will default to
X. Only one field can be an annotation.
articles string... ||
string... are definite or indefinite articles, and should be ignored at the beginning of
T fields when sorting.
the, a and
an are recognized as articles.
bibliography filename... ||
Write out all the references contained in the bibliographic databases
bracket-label string1 string2 string3 |
In the text, bracket each label
string2. An occurrence of
string2 immediately followed by
string1 will be turned into
string3. The default behaviour is
bracket-label \*([. \*(.] ", "
capitalize fields ||
fields to caps and small caps.
.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
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.
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
would attach a disambiguating letter to the year part of the
D field in the reference.
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.
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.
et-al* string m n ||
Control use of
in the evaluation of
@ expressions in label expressions.
If the number of authors needed to make the author sequence
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
t is not less than
n. The default behaviour is
et-al " et al" 2 3
include filename ||
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 is omitted,
it will default to
string2 is also omitted it will also default to
string1. For example,
will restore the default method for joining authors.
join-authors " and " ", " ", and "
When outputting the reference,
define the string
[F to be the references label.
This is the default behaviour; so the negative version
of this command is more useful.
For each reference output a label in the text.
The label will be separated from the surrounding text as described in the
This is the default behaviour; 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.
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
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.
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.
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.
. can be used to indicate the references should be sorted using the
subsection describes the concept of a tentative label.)
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
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 tentative evaluation, called the
is used to gather the information
that normal evaluation needs to disambiguate the label.
Label expressions specified by the
short-label commands are not evaluated tentatively.
Normal and tentative evaluation are the same for all types
of expression other than
@, *, and
The description below applies to normal evaluation,
except where otherwise specified.
The above expressions are listed in order of precedence
| have the same precedence.
field n ||
n-th part of
n is omitted, it defaults to 1.
The characters in
All the authors joined as specified by the
The whole of each authors 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
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,
i-th authors are not the same,
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
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.
The serial number of the reference formatted according to the character
%. 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.
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.
(+) or last
(-) n upper or lower case letters or digits of
expr. Troff special characters (such as
\(a) count as a single letter.
Accent strings are retained but do not count towards the total.
expr converted to lowercase.
expr converted to uppercase.
expr converted to caps and small caps.
expr reversed so that the last name is first.
expr with first names abbreviated.
Note that fields specified in the
abbreviate command are abbreviated before any labels are evaluated.
.a is useful only when you want a field to be abbreviated in a label
but not in a reference.
The year part of
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.
The last name part of
expr1 except that if the last character of
- then it will be replaced by
expr1 expr2 |
The concatenation of
expr1 is non-empty then
expr1 is non-empty
expr2 otherwise an empty string.
expr1 is non-empty
The label is in two parts, which are separated by
expr. Two adjacent two-part labels which have the same first part will be
merged by appending the second part of the second label onto the first
label separated by the string specified in the
separate-label-second-parts command (initially, a comma followed by a space); the resulting label
will also be a two-part label with the same first part as before
merging, and so additional labels can be merged into it.
Note that it is permissible for the first part to be empty;
this maybe desirable for expressions used in the
The same as
expr. Used for grouping.
Each reference starts with a call to the macro
]-. The string
[F will be defined to be the label for this reference,
no-label-in-reference command has been given.
There then follows a series of string definitions,
one for each field:
[X corresponds to field
X. The number register
[P is set to 1 if the
P field contains a range of pages.
[T, [A and
[O number registers are set to 1 according as the
T, A and
O fields end with one of the characters
[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
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
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
In label expressions,
<> expressions are ignored inside