tbl(1) General Commands Manual tbl(1)
Name
tbl - prepare tables for groff documents
Synopsis
tbl [-C] [file ...]
tbl --help
tbl -v
tbl --version
Description
The GNU implementation of tbl is part of the groff(1) document
formatting system. tbl is a troff(1) preprocessor that translates
descriptions of tables embedded in roff(7) input files into the
language understood by troff. It copies the contents of each file to
the standard output stream, except that lines between .TS and .TE are
interpreted as table descriptions. While GNU tbl's input syntax is
highly compatible with AT&T tbl, the output GNU tbl produces cannot be
processed by AT&T troff; GNU troff (or a troff implementing any GNU
extensions employed) must be used. Normally, tbl is not executed
directly by the user, but invoked by specifying the -t option to
groff(1). If no file operands are given on the command line, or if
file is "-", tbl reads the standard input stream.
Overview
tbl expects to find table descriptions between input lines that begin
with .TS (table start) and .TE (table end). Each such table region
encloses one or more table descriptions. Within a table region, table
descriptions beyond the first must each be preceded by an input line
beginning with .T&. This mechanism does not start a new table region;
all table descriptions are treated as part of their .TS/.TE enclosure,
even if they are boxed or have column headings that repeat on
subsequent pages (see below).
(Experienced roff users should observe that tbl is not a roff language
interpreter: the default control character must be used, and no spaces
or tabs are permitted between the control character and the macro name.
These tbl input tokens remain as-is in the output, where they become
ordinary macro calls. Macro packages often define TS, T&, and TE
macros to handle issues of table placement on the page. tbl produces
groff code to define these macros as empty if their definitions do not
exist when the formatter encounters a table region.)
Each table region may begin with region options, and must contain one
or more table definitions; each table definition contains a format
specification followed by one or more input lines (rows) of entries.
These entries comprise the table data.
Region options
The line immediately following the .TS token may specify region
options, keywords that influence the interpretation or rendering of the
region as a whole or all table entries within it indiscriminately.
They must be separated by commas, spaces, or tabs. Those that require
a parenthesized argument permit spaces and tabs between the option's
name and the opening parenthesis. Options accumulate and cannot be
unset within a region once declared; if an option that takes a
parameter is repeated, the last occurrence controls. If present, the
set of region options must be terminated with a semicolon (;).
Any of the allbox, box, doublebox, frame, and doubleframe region
options makes a table "boxed" for the purpose of later discussion.
allbox Enclose each table entry in a box; implies box.
box Enclose the entire table region in a box. As a GNU extension,
the alternative option name frame is also recognized.
center Center the table region with respect to the current indentation
and line length; the default is to left-align it. As a GNU
extension, the alternative option name centre is also
recognized.
decimalpoint(c)
Recognize character c as the decimal separator in columns using
the N (numeric) classifier (see subsection "Column classifiers"
below). This is a GNU extension.
delim(xy)
Recognize characters x and y as start and end delimiters,
respectively, for eqn(1) input, and ignore input between them.
x and y need not be distinct.
doublebox
Enclose the entire table region in a double box; implies box.
As a GNU extension, the alternative option name doubleframe is
also recognized.
expand Spread the table horizontally to fill the available space (line
length minus indentation) by increasing column separation.
Ordinarily, a table is made only as wide as necessary to
accommodate the widths of its entries and its column separations
(whether specified or default). When expand applies to a table
that exceeds the available horizontal space, column separation
is reduced as far as necessary (even to zero). tbl produces
groff input that issues a diagnostic if such compression occurs.
The column modifier x (see below) overrides this option.
linesize(n)
Draw lines or rules (e.g., from box) with a thickness of
n points. The default is the current type size when the region
begins. This option is ignored on terminal devices.
nokeep Don't use roff diversions to manage page breaks. Normally, tbl
employs them to avoid breaking a page within a table row. This
usage can sometimes interact badly with macro packages' own use
of diversions--when footnotes, for example, are employed. This
is a GNU extension.
nospaces
Ignore leading and trailing spaces in table entries. This is a
GNU extension.
nowarn Suppress diagnostic messages produced at document formatting
time when the line or page lengths are inadequate to contain a
table row. This is a GNU extension.
tab(c) Use the character c instead of a tab to separate entries in a
row of table data.
Table format specification
The table format specification is mandatory: it determines the number
of columns in the table and directs how the entries within it are to be
typeset. The format specification is a series of column descriptors.
Each descriptor encodes a classifier followed by zero or more
modifiers. Classifiers are letters (recognized case-insensitively) or
punctuation symbols; modifiers consist of or begin with letters or
numerals. Spaces, tabs, newlines, and commas separate descriptors.
Newlines and commas are special; they apply the descriptors following
them to a subsequent row of the table. (This enables column headings
to be centered or emboldened while the table entries for the data are
not, for instance.) We term the resulting group of column descriptors
a row definition. Within a row definition, separation between column
descriptors (by spaces or tabs) is often optional; only some modifiers,
described below, make separation necessary.
Each column descriptor begins with a mandatory classifier, a character
that selects from one of several arrangements. Some determine the
positioning of table entries within a rectangular cell: centered, left-
aligned, numeric (aligned to a configurable decimal separator), and so
on. Others perform special operations like drawing lines or spanning
entries from adjacent cells in the table. Except for "|", any
classifier can be followed by one or more modifiers; some of these
accept an argument, which in GNU tbl can be parenthesized. Modifiers
select fonts, set the type size, and perform other tasks described
below.
The format specification can occupy multiple input lines, but must
conclude with a dot "." followed by a newline. Each row definition is
applied in turn to one row of the table. The last row definition is
applied to rows of table data in excess of the row definitions.
For clarity in this document's examples, we shall write classifiers in
uppercase and modifiers in lowercase. Thus, "CbCb,LR." defines two
rows of two columns. The first row's entries are centered and
boldfaced; the second and any further rows' first and second columns
are left- and right-aligned, respectively.
The row definition with the most column descriptors determines the
number of columns in the table; any row definition with fewer is
implicitly extended on the right-hand side with L classifiers as many
times as necessary to make the table rectangular.
Column classifiers
The L, R, and C classifiers are the easiest to understand and use.
A, a Center longest entry in this column, left-align remaining
entries in the column with respect to the centered entry, then
indent all entries by one en. Such "alphabetic" entries (hence
the name of the classifier) can be used in the same column as
L-classified entries, as in "LL,AR.". The A entries are often
termed "sub-columns" due to their indentation.
C, c Center entry within the column.
L, l Left-align entry within the column.
N, n Numerically align entry in the column. tbl aligns columns of
numbers vertically at the units place. If multiple decimal
separators are adjacent to a digit, it uses the rightmost one
for vertical alignment. If there is no decimal separator, the
rightmost digit is used for vertical alignment; otherwise, tbl
centers the entry within the column. The roff dummy character
\& in an entry marks the glyph preceding it (if any) as the
units place; if multiple instances occur in the data, the
leftmost is used for alignment.
If N-classified entries share a column with L or R entries, tbl
centers the widest N entry with respect to the widest L or
R entry, preserving the alignment of N entries with respect to
each other.
The appearance of eqn equations within N-classified columns can
be troublesome due to the foregoing textual scan for a decimal
separator. Use the delim region option to make tbl ignore the
data within eqn delimiters for that purpose.
R, r Right-align entry within the column.
S, s Span previous entry on the left into this column.
^ Span entry in the same column from the previous row into this
row.
_, - Replace table entry with a horizontal rule. An empty table
entry is expected to correspond to this classifier; if data are
found there, tbl issues a diagnostic message.
= Replace table entry with a double horizontal rule. An empty
table entry is expected to correspond to this classifier; if
data are found there, tbl issues a diagnostic message.
| Place a vertical rule (line) on the corresponding row of the
table (if two of these are adjacent, a double vertical rule).
This classifier does not contribute to the column count and no
table entries correspond to it. A | to the left of the first
column descriptor or to the right of the last one produces a
vertical rule at the edge of the table; these are redundant (and
ignored) in boxed tables.
To change the table format within a tbl region, use the .T& token at
the start of a line. It is followed by a format specification and
table data, but not region options. The quantity of columns in a new
table format thus introduced cannot increase relative to the previous
table format; in that case, you must end the table region and start
another. If that will not serve because the region uses box options or
the columns align in an undesirable manner, you must design the initial
table format specification to include the maximum quantity of columns
required, and use the S horizontal spanning classifier where necessary
to achieve the desired columnar alignment.
Attempting to horizontally span in the first column or vertically span
on the first row is an error. Non-rectangular span areas are also not
supported.
Column modifiers
Any number of modifiers can follow a column classifier. Arguments to
modifiers, where accepted, are case-sensitive. If the same modifier is
applied to a column specifier more than once, or if conflicting
modifiers are applied, only the last occurrence has effect. The
modifier x is mutually exclusive with e and w, but e is not mutually
exclusive with w; if these are used in combination, x unsets both e
and w, while either e or w overrides x.
b, B Typeset entry in boldface, abbreviating f(B).
d, D Align a vertically spanned table entry to the bottom ("down"),
instead of the center, of its range. This is a GNU extension.
e, E Equalize the widths of columns with this modifier. The column
with the largest width controls. This modifier sets the default
line length used in a text block.
f, F Select the typeface for the table entry. This modifier must be
followed by a font or style name (one or two characters not
starting with a digit), font mounting position (a single digit),
or a name or mounting position of any length in parentheses.
The last form is a GNU extension. (The parameter corresponds to
that accepted by the troff ft request.) A one-character
argument not in parentheses must be separated by one or more
spaces or tabs from what follows.
i, I Typeset entry in an oblique or italic face, abbreviating f(I).
m, M Call a groff macro before typesetting a text block (see
subsection "Text blocks" below). This is a GNU extension. This
modifier must be followed by a macro name of one or two
characters or a name of any length in parentheses. A one-
character macro name not in parentheses must be separated by one
or more spaces or tabs from what follows. The named macro must
be defined before the table region containing this column
modifier is encountered. The macro should contain only simple
groff requests to change text formatting, like adjustment or
hyphenation. The macro is called after the column modifiers b,
f, i, p, and v take effect; it can thus override other column
modifiers.
p, P Set the type size for the table entry. This modifier must be
followed by an integer n with an optional leading sign. If
unsigned, the type size is set to n scaled points. Otherwise,
the type size is incremented or decremented per the sign by
n scaled points. The use of a signed multi-digit number is a
GNU extension. (The parameter corresponds to that accepted by
the troff ps request.) If a type size modifier is followed by a
column separation modifier (see below), they must be separated
by at least one space or tab.
t, T Align a vertically spanned table entry to the top, instead of
the center, of its range.
u, U Move the column up one half-line, "staggering" the rows. This
is a GNU extension.
v, V Set the vertical spacing to be used in a text block. This
modifier must be followed by an integer n with an optional
leading sign. If unsigned, the vertical spacing is set to
n points. Otherwise, the vertical spacing is incremented or
decremented per the sign by n points. The use of a signed
multi-digit number is a GNU extension. (This parameter
corresponds to that accepted by the troff vs request.) If a
vertical spacing modifier is followed by a column separation
modifier (see below), they must be separated by at least one
space or tab.
w, W Set the column's minimum width. This modifier must be followed
by a number, which is either a unitless integer, or a roff
horizontal measurement in parentheses. Parentheses are required
if the width is to be followed immediately by an explicit column
separation (alternatively, follow the width with one or more
spaces or tabs). If no unit is specified, ens are assumed.
This modifier sets the default line length used in a text block.
x, X Expand the column. After computing the column widths,
distribute any remaining line length evenly over all columns
bearing this modifier. Applying the x modifier to more than one
column is a GNU extension. This modifier sets the default line
length used in a text block.
z, Z Ignore the table entries corresponding to this column for width
calculation purposes; that is, compute the column's width using
only the information in its descriptor.
n A numeric suffix on a column descriptor sets the separation
distance (in ens) from the succeeding column; the default
separation is 3n. This separation is proportionally multiplied
if the expand region option is in effect; in the case of tables
wider than the output line length, this separation might be
zero. A negative separation cannot be specified. A separation
amount after the last column in a row is nonsensical and
provokes a diagnostic from tbl.
Table data
The table data come after the format specification. Each input line
corresponds to a table row, except that a backslash at the end of a
line of table data continues an entry on the next input line. (Text
blocks, discussed below, also spread table entries across multiple
input lines.) Table entries within a row are separated in the input by
a tab character by default; see the tab region option above. Excess
entries in a row of table data (those that have no corresponding column
descriptor, not even an implicit one arising from rectangularization of
the table) are discarded with a diagnostic message. roff control lines
are accepted between rows of table data and within text blocks. If you
wish to visibly mark an empty table entry in the document source,
populate it with the \& roff dummy character. The table data are
interrupted by a line consisting of the .T& input token, and conclude
with the line .TE.
Ordinarily, a table entry is typeset rigidly. It is not filled,
broken, hyphenated, adjusted, or populated with additional inter-
sentence space. tbl instructs the formatter to measure each table
entry as it occurs in the input, updating the width required by its
corresponding column. If the z modifier applies to the column, this
measurement is ignored; if w applies and its argument is larger than
this width, that argument is used instead. In contrast to conventional
roff input (within a paragraph, say), changes to text formatting, such
as font selection or vertical spacing, do not persist between entries.
Several forms of table entry are interpreted specially.
o If a table row contains only an underscore or equals sign (_ or =), a
single or double horizontal rule (line), respectively, is drawn
across the table at that point.
o A table entry containing only _ or = on an otherwise populated row is
replaced by a single or double horizontal rule, respectively, joining
its neighbors.
o Prefixing a lone underscore or equals sign with a backslash also has
meaning. If a table entry consists only of \_ or \= on an otherwise
populated row, it is replaced by a single or double horizontal rule,
respectively, that does not (quite) join its neighbors.
o A table entry consisting of \Rx, where x is any roff ordinary or
special character, is replaced by enough repetitions of the glyph
corresponding to x to fill the column, albeit without joining its
neighbors.
o On any row but the first, a table entry of \^ causes the entry above
it to span down into the current one.
On occasion, these special tokens may be required as literal table
data. To use either _ or = literally and alone in an entry, prefix or
suffix it with the roff dummy character \&. To express \_, \=, or \R,
use a roff escape sequence to interpolate the backslash (\e or \[rs]).
A reliable way to emplace the \^ glyph sequence within a table entry is
to use a pair of groff special character escape sequences (\[rs]\[ha]).
Rows of table entries can be interleaved with groff control lines;
these do not count as table data. On such lines the default control
character (.) must be used (and not changed); the no-break control
character is not recognized. To start the first table entry in a row
with a dot, precede it with the roff dummy character \&.
Text blocks
An ordinary table entry's contents can make a column, and therefore the
table, excessively wide; the table then exceeds the line length of the
page, and becomes ugly or is exposed to truncation by the output
device. When a table entry requires more conventional typesetting,
breaking across more than one output line (and thereby increasing the
height of its row), it can be placed within a text block.
tbl interprets a table entry beginning with "T{" at the end of an input
line not as table data, but as a token starting a text block.
Similarly, "T}" at the start of an input line ends a text block; it
must also end the table entry. Text block tokens can share an input
line with other table data (preceding T{ and following T}). Input
lines between these tokens are formatted in a diversion by troff. Text
blocks cannot be nested. Multiple text blocks can occur in a table
row.
Text blocks are formatted as was the text prior to the table, modified
by applicable column descriptors. Specifically, the classifiers A, C,
L, N, R, and S determine a text block's alignment within its cell, but
not its adjustment. Add na or ad requests to the beginning of a text
block to alter its adjustment distinctly from other text in the
document. As with other table entries, when a text block ends, any
alterations to formatting parameters are discarded. They do not affect
subsequent table entries, not even other text blocks.
If w or x modifiers are not specified for all columns of a text block's
span, the default length of the text block (more precisely, the line
length used to process the text block diversion) is computed as
LxC/(N+1), where L is the current line length, C the number of columns
spanned by the text block, and N the number of columns in the table.
If necessary, you can also control a text block's width by including an
ll (line length) request in it prior to any text to be formatted.
Because a diversion is used to format the text block, its height and
width are subsequently available in the registers dn and dl,
respectively.
roff interface
The register TW stores the width of the table region in basic units; it
can't be used within the region itself, but is defined before the .TE
token is output so that a groff macro named TE can make use of it. T.
is a Boolean-valued register indicating whether the bottom of the table
is being processed. The #T register marks the top of the table. Avoid
using these names for any other purpose.
tbl also defines a macro T# to produce the bottom and side lines of a
boxed table. While tbl itself arranges for the output to include a
call of this macro at the end of such a table, it can also be used by
macro packages to create boxes for multi-page tables by calling it from
a page footer macro that is itself called by a trap planted near the
bottom of the page. See section "Limitations" below for more on multi-
page tables.
GNU tbl internally employs register, string, macro, and diversion names
beginning with the numeral 3. A document to be preprocessed with GNU
tbl should not use any such identifiers.
Interaction with eqn
tbl should always be called before eqn(1). (groff(1) automatically
arranges preprocessors in the correct order.) Don't call the EQ and EN
macros within tables; instead, set up delimiters in your eqn input and
use the delim region option so that tbl will recognize them.
GNU tbl enhancements
In addition to extensions noted above, GNU tbl removes constraints
endured by users of AT&T tbl.
o Region options can be specified in any lettercase.
o There is no limit on the number of columns in a table, regardless of
their classification, nor any limit on the number of text blocks.
o All table rows are considered when deciding column widths, not just
those occurring in the first 200 input lines of a region. Similarly,
table continuation (.T&) tokens are recognized outside a region's
first 200 input lines.
o Numeric and alphabetic entries may appear in the same column.
o Numeric and alphabetic entries may span horizontally.
Using GNU tbl within macros
You can embed a table region inside a macro definition. However, since
tbl writes its own macro definitions at the beginning of each table
region, it is necessary to call end macros instead of ending macro
definitions with "..". Additionally, the escape character must be
disabled.
Not all tbl features can be exercised from such macros because tbl is a
roff preprocessor: it sees the input earlier than troff does. For
example, vertically aligning decimal separators fails if the numbers
containing them occur as macro or string parameters; the alignment is
performed by tbl itself, which sees only \$1, \$2, and so on, and
therefore can't recognize a decimal separator that only appears later
when troff interpolates a macro or string definition.
Using tbl macros within conditional input (that is, contingent upon an
if, ie, el, or while request) can result in misleading line numbers in
subsequent diagnostics. tbl unconditionally injects its output into
the source document, but the conditional branch containing it may not
be taken, and if it is not, the lf requests that tbl injects to restore
the source line number cannot take effect. Consider copying the input
line counter register c. and restoring its value at a convenient
location after applicable arithmetic.
Options
--help displays a usage message, while -v and --version show version
information; all exit afterward.
-C Enable AT&T compatibility mode: recognize .TS and .TE even when
followed by a character other than space or newline.
Furthermore, interpret the uninterpreted leader escape sequence
\a.
Limitations
Multi-page tables, if boxed and/or if you want their column headings
repeated after page breaks, require support at the time the document is
formatted. A convention for such support has arisen in macro packages
such as ms, mm, and me. To use it, follow the .TS token with a space
and then "H"; this will be interpreted by the formatter as a TS macro
call with an H argument. Then, within the table data, call the TH
macro; this informs the macro package where the headings end. If your
table has no such heading rows, or you do not desire their repetition,
call TH immediately after the table format specification. If a multi-
page table is boxed or has repeating column headings, do not enclose it
with keep/release macros, or divert it in any other way. Further, the
bp request will not cause a page break in a "TS H" table. Define a
macro to wrap bp: invoke it normally if there is no current diversion.
Otherwise, pass the macro call to the enclosing diversion using the
transparent line escape sequence \!; this will "bubble up" the page
break to the output device. See section "Examples" below for a
demonstration.
Double horizontal rules are not supported by grotty(1); single rules
are used instead. grotty also ignores half-line motions, so the u
column modifier has no effect. On terminal devices ("nroff mode"),
horizontal rules and box borders occupy a full vee of space; this
amount is doubled for doublebox tables. Tables using these features
thus require more vertical space in nroff mode than in troff mode:
write ne requests accordingly. Vertical rules between columns are
drawn in the space between columns in nroff mode; using double vertical
rules and/or reducing the column separation below the default can make
them ugly or overstrike them with table data.
A text block within a table must be able to fit on one page.
Using \a to put leaders in table entries does not work in GNU tbl,
except in compatibility mode. This is correct behavior: \a is an
uninterpreted leader. You can still use the roff leader character
(Control+A) or define a string to use \a as it was designed: to be
interpreted only in copy mode.
.ds a \a
.TS
box center tab(;);
Lw(2i)0 L.
Population\*a;6,327,119
.TE
+------------------------------+
|Population? 6,327,119 |
+------------------------------+
A leading and/or trailing | in a format specification, such as
"|LCR|.", produces an en space between the vertical rules and the
content of the adjacent columns. If no such space is desired (so that
the rule abuts the content), you can introduce "dummy" columns with
zero separation and empty corresponding table entries before and/or
after.
.TS
center tab(#);
R0|L C R0|L.
_
#levulose#glucose#dextrose#
_
.TE
These dummy columns have zero width and are therefore invisible;
unfortunately they usually don't work as intended on terminal devices.
Examples
It can be easier to acquire the language of tbl through examples than
formal description, especially at first.
.TS
box center tab(#);
Cb Cb
L L.
Ability#Application
Strength#crushes a tomato
Dexterity#dodges a thrown tomato
Constitution#eats a month-old tomato without becoming ill
Intelligence#knows that a tomato is a fruit
Wisdom#chooses \f[I]not\f[] to put tomato in a fruit salad
Charisma#sells obligate carnivores tomato-based fruit salads
.TE
+-------------------------------------------------------------------+
| Ability Application |
|Strength crushes a tomato |
|Dexterity dodges a thrown tomato |
|Constitution eats a month-old tomato without becoming ill |
|Intelligence knows that a tomato is a fruit |
|Wisdom chooses not to put tomato in a fruit salad |
|Charisma sells obligate carnivores tomato-based fruit salads |
+-------------------------------------------------------------------+
The A and N column classifiers can be easier to grasp in visual
rendering than in description.
.TS
center tab(;);
CbS,LN,AN.
Daily energy intake (in MJ)
Macronutrients
.\" assume 3 significant figures of precision
Carbohydrates;4.5
Fats;2.25
Protein;3
.T&
LN,AN.
Mineral
Pu-239;14.6
_
.T&
LN.
Total;\[ti]24.4
.TE
Daily energy intake (in MJ)
Macronutrients
Carbohydrates 4.5
Fats 2.25
Protein 3
Mineral
Pu-239 14.6
----------------------------
Total ~24.4
Next, we'll lightly adapt a compact presentation of spanning, vertical
alignment, and zero-width column modifiers from the mandoc reference
for its tbl interpreter. It rewards close study.
.TS
box center tab(:);
Lz S | Rt
Ld| Cb| ^
^ | Rz S.
left:r
l:center:
:right
.TE
+-----------+---+
|left | r |
|l | center | |
| | right |
+--+------------+
Row staggering is not visually achievable on terminal devices, but a
table using it can remain comprehensible nonetheless.
.TS
center tab(|);
Cf(BI) Cf(BI) Cf(B), C C Cu.
n|n\f[B]\[tmu]\f[]n|difference
1|1
2|4|3
3|9|5
4|16|7
5|25|9
6|36|11
.TE
n nxn difference
1 1
2 4 3
3 9 5
4 16 7
5 25 9
6 36 11
Some tbl features cannot be illustrated in the limited environment of a
portable man page.
We can define a macro outside of a tbl region that we can call from
within it to cause a page break inside a multi-page boxed table. You
can choose a different name; be sure to change both occurrences of
"BP".
.de BP
. ie '\\n(.z'' .bp \\$1
. el \!.BP \\$1
..
See also
"Tbl--A Program to Format Tables", by M. E. Lesk, 1976 (revised 16
January 1979), AT&T Bell Laboratories Computing Science Technical
Report No. 49.
The spanning example above was taken from mandoc's man page for its tbl
implementation <https://man.openbsd.org/tbl.7>.
groff(1), troff(1)
groff 1.23.0 2 July 2023 tbl(1)
groff 1.23.0 - Generated Sat Dec 23 08:39:01 CST 2023