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tbl - format tables for troff


tbl [-Cv] [files ...]


This manual page describes the GNU version of tbl, which is part of the groff document
formatting system. tbl compiles descriptions of tables embedded within troff input files
into commands that are understood by troff. Normally, it should be invoked using the -t
option of groff. It is highly compatible with Unix tbl. The output generated by GNU tbl
cannot be processed with Unix troff; it must be processed with GNU troff. If no files are
given on the command line or a filename of - is given, the standard input is read.


-C Enable compatibility mode to recognize .TS and .TE even when followed by a
character other than space or newline. Leader characters (\a) are handled as

-v Print the version number.


tbl expects to find table descriptions wrapped in the .TS (table start) and .TE (table
end) macros. Within each such table sections, another table can be defined by using the
request .T& before the final command .TE. Each table definition has the following

Global options
This is optional. This table part can use several of these options distributed in
1 or more lines. The global option part must always be finished by a semi-colon ;

Table format specification
This part must be given, it is not optional. It determines the number of columns
(cells) of the table. Moreover each cell is classified by being central, left
adjusted, or numerical, etc. This specification can have several lines, but must
be finished by a dot . at the end of the last line. After each cell definition,
column specifiers can be appended, but that's optional.

Cells are separated by a tab character by default. That can be changed by the global
option tbl(c), where c is an arbitrary character.


The easiest table definition is.
c c c .
This is centered
Well, this also
By using c c c, each cell in the whole table will be centered. The separating character
is here the default tab.

The result is

This is centered
Well, this also

This definition is identical to
Here, the separating tab character is changed to the letter @.

Moreover a title can be added and the centering directions can be changed to many other
c s s
l c n .
The result is

left centers 123
another number 75
Here l means left-justified, and n means numerical, which is here right-justified.


Global options
The line immediately following the .TS macro may contain any of the following global
options (ignoring the case of characters – Unix tbl only accepts options with all
characters lowercase or all characters uppercase), separated by spaces, tabs, or commas:

allbox Enclose each item of the table in a box.

box Enclose the table in a box.

center Center the table (default is left-justified). The alternative keyword name centre
is also recognized (this is a GNU tbl extension).

Set the character to be recognized as the decimal point in numeric columns (GNU tbl

Use x and y as start and end delimiters for eqn(1).

Enclose the table in a double box.

Same as doublebox (GNU tbl only).

expand Make the table as wide as the current line length (providing a column separation
factor). Ignored if one or more ‘x’ column specifiers are used (see below).

In case the sum of the column widths is larger than the current line length, the
column separation factor is set to zero; such tables extend into the right margin,
and there is no column separation at all.

frame Same as box (GNU tbl only).

Set lines or rules (e.g. from box) in n-point type.

nokeep Don't use diversions to prevent page breaks (GNU tbl only). Normally tbl attempts
to prevent undesirable breaks in boxed tables by using diversions. This can
sometimes interact badly with macro packages own use of diversions, when footnotes,
for example, are used.

Ignore leading and trailing spaces in data items (GNU tbl only).

nowarn Turn off warnings related to tables exceeding the current line width (GNU tbl

tab(x) Use the character x instead of a tab to separate items in a line of input data.

The global options must end with a semicolon. There might be whitespace between an option
and its argument in parentheses.

Table format specification
After global options come lines describing the format of each line of the table. Each
such format line describes one line of the table itself, except that the last format line
(which you must end with a period) describes all remaining lines of the table. A single-
key character describes each column of each line of the table. Key characters can be
separated by spaces or tabs. You may run format specifications for multiple lines
together on the same line by separating them with commas.

You may follow each key character with specifiers that determine the font and point size
of the corresponding item, that determine column width, inter-column spacing, etc.

The longest format line defines the number of columns in the table; missing format
descriptors at the end of format lines are assumed to be L. Extra columns in the data
(which have no corresponding format entry) are ignored.

The available key characters are:

a,A Center longest line in this column and then left-justifies all other lines in this
column with respect to that centered line. The idea is to use such alphabetic
subcolumns (hence the name of the key character) in combination with L; they are
called subcolumns because A items are indented by 1n relative to L entries.

item one;1
subitem two;2
subitem three;3
item eleven;11
subitem twentytwo;22
subitem thirtythree;33


item one 1
subitem two 2
subitem three 3
item eleven 11
subitem twentytwo 22
subitem thirtythree 33

c,C Center item within the column.

l,L Left-justify item within the column.

n,N Numerically justify item in the column: Units positions of numbers are aligned
vertically. If there is one or more dots adjacent to a digit, use the rightmost
one for vertical alignment. If there is no dot, use the rightmost digit for
vertical alignment; otherwise, center the item within the column. Alignment can be
forced to a certain position using ‘\&’; if there is one or more instances of this
special (non-printing) character present within the data, use the leftmost one for
alignment. Example:




If numerical entries are combined with L or R entries – this can happen if the
table format is changed with .T& – center the widest number (of the data entered
under the N specifier regime) relative to the widest L or R entry, preserving the
alignment of all numerical entries. Contrary to A type entries, there is no extra

Using equations (to be processed with eqn) within columns which use the N specifier
is problematic in most cases due to tbl's algorithm for finding the vertical
alignment, as described above. Using the global delim option, however, it is
possible to make tbl ignore the data within eqn delimiters for that purpose.

r,R Right-justify item within the column.

s,S Span previous item on the left into this column. Not allowed for the first column.

^ Span down entry from previous row in this column. Not allowed for the first row.

_,- Replace this entry with a horizontal line. Note that ‘_’ and ‘-’ can be used for
table fields only, not for column separator lines.

= Replace this entry with a double horizontal line. Note that ‘=’ can be used for
table fields only, not for column separator lines.

| The corresponding column becomes a vertical rule (if two of these are adjacent, a
double vertical rule).

A vertical bar to the left of the first key letter or to the right of the last one
produces a line at the edge of the table.

To change the data format within a table, use the .T& command (at the start of a line).
It is followed by format and data lines (but no global options) similar to the .TS

Column specifiers
Here are the specifiers that can appear in suffixes to column key letters (in any order):

b,B Short form of fB (make affected entries bold).

d,D Start an item that vertically spans rows, using the ‘^’ column specifier or ‘\^’
data item, at the bottom of its range rather than vertically centering it (GNU tbl
only). Example:

tab(;) allbox;
l l
l ld
r ^
l rd.


│0000 │ foobar │
│1111 │ │
│2222 │ │
├─────┤ │
│ r │ foo │
│3333 │ │
│4444 │ bar │
e,E Make equally-spaced columns. All columns marked with this specifier get the same
width; this happens after the affected column widths have been computed (this means
that the largest width value rules).

f,F Either of these specifiers may be followed by a font name (either one or two
characters long), font number (a single digit), or long name in parentheses (the
last form is a GNU tbl extension). A one-letter font name must be separated by one
or more blanks from whatever follows.

i,I Short form of fI (make affected entries italic).

m,M This is a GNU tbl extension. Either of these specifiers may be followed by a macro
name (either one or two characters long), or long name in parentheses. A one-
letter macro name must be separated by one or more blanks from whatever follows.
The macro which name can be specified here must be defined before creating the
table. It is called just before the table's cell text is output. As implemented
currently, this macro is only called if block input is used, that is, text between
‘T{’ and ‘T}’. The macro should contain only simple troff requests to change the
text block formatting, like text adjustment, hyphenation, size, or font. The macro
is called after other cell modifications like b, f or v are output. Thus the macro
can overwrite other modification specifiers.

p,P Followed by a number, this does a point size change for the affected fields. If
signed, the current point size is incremented or decremented (using a signed number
instead of a signed digit is a GNU tbl extension). A point size specifier followed
by a column separation number must be separated by one or more blanks.

t,T Start an item vertically spanning rows at the top of its range rather than
vertically centering it.

u,U Move the corresponding column up one half-line.

v,V Followed by a number, this indicates the vertical line spacing to be used in a
multi-line table entry. If signed, the current vertical line spacing is
incremented or decremented (using a signed number instead of a signed digit is a
GNU tbl extension). A vertical line spacing specifier followed by a column
separation number must be separated by one or more blanks. No effect if the
corresponding table entry isn't a text block.

w,W Minimum column width value. Must be followed either by a troff(1) width expression
in parentheses or a unitless integer. If no unit is given, en units are used.
Also used as the default line length for included text blocks. If used multiple
times to specify the width for a particular column, the last entry takes effect.

x,X An expanded column. After computing all column widths without an x specifier, use
the remaining line width for this column. If there is more than one expanded
column, distribute the remaining horizontal space evenly among the affected columns
(this is a GNU extension). This feature has the same effect as specifying a
minimum column width.

z,Z Ignore the corresponding column for width-calculation purposes, this is, don't use
the fields but only the specifiers of this column to compute its width.

A number suffix on a key character is interpreted as a column separation in en units
(multiplied in proportion if the expand option is on – in case of overfull tables this
might be zero). Default separation is 3n.

The column specifier x is mutually exclusive with e and w (but e is not mutually exclusive
with w); if specified multiple times for a particular column, the last entry takes effect:
x unsets both e and w, while either e or w overrides x.

Table data
The format lines are followed by lines containing the actual data for the table, followed
finally by .TE. Within such data lines, items are normally separated by tab characters
(or the character specified with the tab option). Long input lines can be broken across
multiple lines if the last character on the line is ‘\’ (which vanishes after

Note that tbl computes the column widths line by line, applying \w on each entry which
isn't a text block. As a consequence, constructions like


fail; you must either say




A dot starting a line, followed by anything but a digit is handled as a troff command,
passed through without changes. The table position is unchanged in this case.

If a data line consists of only ‘_’ or ‘=’, a single or double line, respectively, is
drawn across the table at that point; if a single item in a data line consists of only ‘_’
or ‘=’, then that item is replaced by a single or double line, joining its neighbours. If
a data item consists only of ‘\_’ or ‘\=’, a single or double line, respectively, is drawn
across the field at that point which does not join its neighbours.

A data item consisting only of ‘\Rx’ (‘x’ any character) is replaced by repetitions of
character ‘x’ as wide as the column (not joining its neighbours).

A data item consisting only of ‘\^’ indicates that the field immediately above spans
downward over this row.

Text blocks
A text block can be used to enter data as a single entry which would be too long as a
simple string between tabs. It is started with ‘T{’ and closed with ‘T}’. The former
must end a line, and the latter must start a line, probably followed by other data columns
(separated with tabs or the character given with the tab global option).

By default, the text block is formatted with the settings which were active before
entering the table, possibly overridden by the m, v, and w tbl specifiers. For example,
to make all text blocks ragged-right, insert .na right before the starting .TS (and .ad
after the table).

If either ‘w’ or ‘x[cq] specifiers are not given for all columns of a text block span, the
default length of the text block (to be more precise, 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 total number of columns in
the table. Note, however, that the actual diversion width as returned in register \n[dl]
is used eventually as the text block width. If necessary, you can also control the text
block width with a direct insertion of a .ll request right after ‘T{’.

The number register \n[TW] holds the table width; it can't be used within the table itself
but is defined right before calling .TE so that this macro can make use of it.

tbl also defines a macro .T# which produces the bottom and side lines of a boxed table.
While tbl does call this macro itself at the end of the table, it can be used by macro
packages to create boxes for multi-page tables by calling it within the page footer. An
example of this is shown by the -ms macros which provide this functionality if a table
starts with .TS H instead of the standard call to the .TS macro.


tbl(1) should always be called before eqn(1) (groff(1) automatically takes care of the
correct order of preprocessors).


There is no limit on the number of columns in a table, nor any limit on the number of text
blocks. All the lines of a table are considered in deciding column widths, not just the
first 200. Table continuation (.T&) lines are not restricted to the first 200 lines.

Numeric and alphabetic items may appear in the same column.

Numeric and alphabetic items may span horizontally.

tbl uses register, string, macro and diversion names beginning with the digit 3. When
using tbl you should avoid using any names beginning with a 3.


Since tbl defines its own macros (right before each table) it is necessary to use an ‘end-
of-macro’ macro. Additionally, the escape character has to be switched off. Here an

.de ATABLE ..
allbox tab(;);
.ATABLE A table
.ATABLE Another table
.ATABLE And "another one"

Note, however, that not all features of tbl can be wrapped into a macro because tbl sees
the input earlier than troff. For example, number formatting with vertically aligned
decimal points fails if those numbers are passed on as macro parameters because decimal
point alignment is handled by tbl itself: It only sees ‘\$1’, ‘\$2’, etc., and therefore
can't recognize the decimal point.

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