.\"	Id: tbl.7,v 1.34 2019/03/02 21:03:02 schwarze Exp 
.\"
.\" Copyright (c) 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
.\" Copyright (c) 2014,2015,2017,2018,2019 Ingo Schwarze <schwarze@openbsd.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
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.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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.\"
.Dd March 2, 2019
.Dt TBL 7
.Os
.Sh NAME
.Nm tbl
.Nd tbl language reference for mandoc
.Sh DESCRIPTION
The
.Nm tbl
language formats tables.
It is used within
.Xr mdoc 7
and
.Xr man 7
pages.
This manual describes the subset of the
.Nm
language accepted by the
.Xr mandoc 1
utility.
.Pp
Each table is started with a
.Xr roff 7
.Ic \&TS
macro, consist of at most one line of
.Sx Options ,
one or more
.Sx Layout
lines, one or more
.Sx Data
lines, and ends with a
.Ic \&TE
macro.
All input must be 7-bit ASCII.
.Ss Options
If the first input line of a table ends with a semicolon, it contains
case-insensitive options separated by spaces, tabs, or commas.
Otherwise, it is interpreted as the first
.Sx Layout
line.
.Pp
The following options are available.
Some of them require arguments enclosed in parentheses:
.Bl -tag -width Ds
.It Cm allbox
Draw a single-line box around each table cell.
.It Cm box
Draw a single-line box around the table.
For GNU compatibility, this may also be invoked with
.Cm frame .
.It Cm center
Center the table instead of left-adjusting it.
For GNU compatibility, this may also be invoked with
.Cm centre .
.It Cm decimalpoint
Use the single-character argument as the decimal point with the
.Cm n
layout key.
This is a GNU extension.
.It Cm delim
Use the two characters of the argument as
.Xr eqn 7
delimiters.
Currently unsupported.
.It Cm doublebox
Draw a double-line box around the table.
For GNU compatibility, this may also be invoked with
.Cm doubleframe .
.It Cm expand
Increase the width of the table to the current line length.
Currently ignored.
.It Cm linesize
Draw lines with the point size given by the unsigned integer argument.
Currently ignored.
.It Cm nokeep
Allow page breaks within the table.
This is a GNU extension and currently ignored.
.It Cm nospaces
Ignore leading and trailing spaces in data cells.
This is a GNU extension and currently ignored.
.It Cm nowarn
Suppress warnings about tables exceeding the current line length.
This is a GNU extension and currently ignored.
.It Cm tab
Use the single-character argument as a delimiter between data cells.
By default, the horizontal tabulator character is used.
.El
.Ss Layout
The table layout follows an
.Sx Options
line or a
.Xr roff 7
.Ic \&TS
or
.Ic \&T&
macro.
Each layout line specifies how one line of
.Sx Data
is formatted.
The last layout line ends with a full stop.
It also applies to all remaining data lines.
Multiple layout lines can be joined by commas on a single physical
input line.
.Pp
Each layout line consists of one or more layout cell specifications,
optionally separated by whitespace.
The following case-insensitive key characters start a new cell
specification:
.Bl -tag -width 2n
.It Cm c
Center the string in this cell.
.It Cm r
Right-justify the string in this cell.
.It Cm l
Left-justify the string in this cell.
.It Cm n
Justify a number around its last decimal point.
If no decimal point is found in the number,
it is assumed to trail the number.
.It Cm s
Horizontally span columns from the last
.Pf non- Cm s
layout cell.
It is an error if a column span follows a
.Cm _
or
.Cm =
cell, or comes first on a layout line.
The combined cell as a whole consumes only one cell
of the corresponding data line.
.It Cm a
Left-justify a string and pad with one space.
.It Cm \(ha
Vertically span rows from the last
.Pf non- Cm \(ha
layout cell.
It is an error to invoke a vertical span on the first layout line.
Unlike a horizontal span, a vertical span consumes a data cell
and discards the content.
.It Cm _
Draw a single horizontal line in this cell.
This consumes a data cell and discards the content.
It may also be invoked with
.Cm \- .
.It Cm =
Draw a double horizontal line in this cell.
This consumes a data cell and discards the content.
.El
.Pp
Each cell key may be followed by zero or more of the following
case-insensitive modifiers:
.Bl -tag -width 2n
.It Cm b
Use a bold font for the contents of this cell.
.It Cm d
Move content down to the last row of this vertical span.
Currently ignored.
.It Cm e
Make this column wider to match the maximum width
of any other column also having the
.Cm e
modifier.
.It Cm f
The next character selects the font to use for this cell.
See the
.Xr roff 7
manual for supported one-character font names.
.It Cm i
Use an italic font for the contents of this cell.
.It Cm m
Specify a cell start macro.
This is a GNU extension and currently unsupported.
.It Cm p
Set the point size to the following unsigned argument,
or change it by the following signed argument.
Currently ignored.
.It Cm v
Set the vertical line spacing to the following unsigned argument,
or change it by the following signed argument.
Currently ignored.
.It Cm t
Do not vertically center content in this vertical span,
leave it in the top row.
Currently ignored.
.It Cm u
Move cell content up by half a table row.
Currently ignored.
.It Cm w
Specify a minimum column width.
.It Cm x
After determining the width of all other columns, distribute the
rest of the line length among all columns having the
.Cm x
modifier.
.It Cm z
Do not use this cell for determining the width of this column.
.It Cm \&|
Draw a single vertical line to the right of this cell.
.It Cm ||
Draw a double vertical line to the right of this cell.
.El
.Pp
If a modifier consists of decimal digits,
it specifies a minimum spacing in units of
.Cm n
between this column and the next column to the right.
The default is 3.
If there is a vertical line, it is drawn inside the spacing.
.Ss Data
The data section follows the last
.Sx Layout
line.
Each data line consists of one or more data cells, delimited by
.Cm tab
characters.
.Pp
If a data cell contains only the two bytes
.Ql \e\(ha ,
the cell above spans to this row, as if the layout specification
of this cell were
.Cm \(ha .
.Pp
If a data cell contains only the single character
.Ql _
or
.Ql = ,
a single or double horizontal line is drawn across the cell,
joining its neighbours.
If a data cell contains only the two character sequence
.Ql \e_
or
.Ql \e= ,
a single or double horizontal line is drawn inside the cell,
not joining its neighbours.
If a data line contains nothing but the single character
.Ql _
or
.Ql = ,
a horizontal line across the whole table is inserted
without consuming a layout row.
.Pp
In place of any data cell, a text block can be used.
It starts with
.Ic \&T{
at the end of a physical input line.
Input line breaks inside the text block
neither end the text block nor its data cell.
It only ends if
.Ic \&T}
occurs at the beginning of a physical input line and is followed
by an end-of-cell indicator.
If the
.Ic \&T}
is followed by the end of the physical input line, the text block,
the data cell, and the data line ends at this point.
If the
.Ic \&T}
is followed by the
.Cm tab
character, only the text block and the data cell end,
but the data line continues with the data cell following the
.Cm tab
character.
If
.Ic \&T}
is followed by any other character, it does not end the text block,
which instead continues to the following physical input line.
.Sh EXAMPLES
String justification and font selection:
.Bd -literal -offset indent
\&.TS
rb c  lb
r  ci l.
r	center	l
ri	ce	le
right	c	left
\&.TE
.Ed
.Bd -filled -offset indent
.TS
rb c  lb
r  ci l.
r	center	l
ri	ce	le
right	c	left
.TE
.Ed
.Pp
Some ports in
.Ox 6.1
to show number alignment and line drawing:
.Bd -literal -offset indent
\&.TS
box tab(:);
r| l
r  n.
software:version
_
AFL:2.39b
Mutt:1.8.0
Ruby:1.8.7.374
TeX Live:2015
\&.TE
.Ed
.Bd -filled -offset indent
.TS
box tab(:);
r| l
r  n.
software:version
_
AFL:2.39b
Mutt:1.8.0
Ruby:1.8.7.374
TeX Live:2015
.TE
.Ed
.sp 2v
Spans and skipping width calculations:
.Bd -literal -offset indent
\&.TS
box tab(:);
lz  s | rt
lt| cb| \(ha
\(ha | rz  s.
left:r
l:center:
:right
\&.TE
.Ed
.Bd -filled -offset indent
.TS
box tab(:);
lz  s | rt
lt| cb| ^
^ | rz  s.
left:r
l:center:
:right
.TE
.Ed
.sp 2v
Text blocks, specifying spacings and specifying and equalizing
column widths, putting lines into individual cells, and overriding
.Cm allbox :
.Bd -literal -offset indent
\&.TS
allbox tab(:);
le le||7 lw10.
The fourth line:_:line 1
of this column:=:line 2
determines:\_:line 3
the column width.:T{
This text is too wide to fit into a column of width 17.
T}:line 4
T{
No break here.
T}::line 5
\&.TE
.Ed
.Bd -filled -offset indent
.TS
allbox tab(:);
le le||7 lw10.
The fourth line:_:line 1
of this column:=:line 2
determines:\_:line 3
the column width.:T{
This text is too wide to fit into a column of width 17.
T}:line 4
T{
No break here.
T}::line 5
.TE
.Ed
.sp 2v
These examples were constructed to demonstrate many
.Nm
features in a compact way.
In real manual pages, keep tables as simple as possible.
They usually look better, are less fragile, and are more portable.
.Sh COMPATIBILITY
The
.Xr mandoc 1
implementation of
.Nm
doesn't support
.Xr mdoc 7
and
.Xr man 7
macros and
.Xr eqn 7
equations inside tables.
.Sh SEE ALSO
.Xr mandoc 1 ,
.Xr man 7 ,
.Xr mandoc_char 7 ,
.Xr mdoc 7 ,
.Xr roff 7
.Rs
.%A M. E. Lesk
.%T Tbl\(emA Program to Format Tables
.%D June 11, 1976
.Re
.Sh HISTORY
The tbl utility, a preprocessor for troff, was originally written by M.
E. Lesk at Bell Labs in 1975.
The GNU reimplementation of tbl, part of the groff package, was released
in 1990 by James Clark.
A standalone tbl implementation was written by Kristaps Dzonsons in
2010.
This formed the basis of the implementation that first appeared in
.Ox 4.9
as a part of the
.Xr mandoc 1
utility.
.Sh AUTHORS
This
.Nm
reference was written by
.An Kristaps Dzonsons Aq Mt kristaps@bsd.lv
and
.An Ingo Schwarze Aq Mt schwarze@openbsd.org .
.Sh BUGS
In
.Fl T
.Cm utf8
output mode, heavy lines are drawn instead of double lines.
This cannot be improved because the Unicode standard only provides
an incomplete set of box drawing characters with double lines,
whereas it provides a full set of box drawing characters
with heavy lines.
It is unlikely this can be improved in the future because the box
drawing characters are already marked in Unicode as characters
intended only for backward compatibility with legacy systems,
and their use is not encouraged.
So it seems unlikely that the missing ones might get added in the future.