Manual: tbl
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 defini‐
tion 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 ter‐
minated 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 rec‐
ognized.
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 be‐
tween 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 en‐
tries within it are to be typeset. The format specification is a series of column descriptors. Each descriptor en‐
codes 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 sep‐
arate 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, separa‐
tion 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 mul‐
tiple 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 classi‐
fier; 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 hor‐
izontal 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 exten‐
sion. 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 lead‐
ing 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 ex‐
tension. (This parameter corresponds to that accepted by the troff vs request.) If a vertical spacing modi‐
fier 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 inte‐
ger, 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 mod‐
ifier 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 ef‐
fect; in the case of tables wider than the output line length, this separation might be zero. A negative sep‐
aration 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 back‐
slash 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 ad‐
ditional 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.
• If a table row contains only an underscore or equals sign (_ or =), a single or double horizontal rule (line), re‐
spectively, is drawn across the table at that point.
• A table entry containing only _ or = on an otherwise populated row is replaced by a single or double horizontal
rule, respectively, joining its neighbors.
• 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.
• A table entry consisting of \Rx, where x is any roff ordinary or special character, is replaced by enough repeti‐
tions of the glyph corresponding to x to fill the column, albeit without joining its neighbors.
• 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 ex‐
ceeds 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 start‐
ing 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. Specifi‐
cally, the classifiers A, C, L, N, R, and S determine a text block's alignment within its cell, but not its adjust‐
ment. 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 dis‐
carded. 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 L×C/(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 avail‐
able 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.
• Region options can be specified in any lettercase.
• 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.
• 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.
• Numeric and alphabetic entries may appear in the same column.
• 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 there‐
fore can't recognize a decimal separator that only appears later when troff interpolates a macro or string defini‐
tion.
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 re‐
store 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 en‐
close 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 bor‐
ders occupy a full vee of space; this amount is doubled for doublebox tables. Tables using these features thus re‐
quire 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 be‐
havior: \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 │
│ │ center │ │
│ l │ 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 n×n 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.
groff(1), troff(1)
groff 1.23.0 2 December 2025 tbl(1)