-.\" $Id: eqn.7,v 1.21 2011/07/23 12:08:43 kristaps Exp $
+.\" $Id: eqn.7,v 1.29 2013/07/13 19:41:16 schwarze Exp $
.\"
.\" Copyright (c) 2011 Kristaps Dzonsons <kristaps@bsd.lv>
.\"
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
-.Dd $Mdocdate: July 23 2011 $
+.Dd $Mdocdate: July 13 2013 $
.Dt EQN 7
.Os
.Sh NAME
.Sh DESCRIPTION
The
.Nm eqn
-language is a equation-formatting language.
+language is an equation-formatting language.
It is used within
.Xr mdoc 7
and
.Xr man 7
.Ux
manual pages.
-This manual describes the subset of the
+It describes the
+.Em structure
+of an equation, not its mathematical meaning.
+This manual describes the
.Nm
language accepted by the
.Xr mandoc 1
-utility.
+utility, which corresponds to the Second Edition eqn specification (see
+.Sx SEE ALSO
+for references).
.Pp
Equations within
.Xr mdoc 7
box : text
| \*q{\*q eqn \*q}\*q
| \*qdefine\*q text text
+ | \*qndefine\*q text text
+ | \*qtdefine\*q text text
| \*qgfont\*q text
| \*qgsize\*q text
| \*qset\*q text text
| font box
| \*qsize\*q text box
| \*qleft\*q text eqn [\*qright\*q text]
-col : \*qlcol\*q | \*qrcol\*q | \*qccol\*q
+col : \*qlcol\*q | \*qrcol\*q | \*qccol\*q | \*qcol\*q
text : [^space\e\*q]+ | \e\*q.*\e\*q
-pile : \*qlpile\*q | \*qcpile\*q | \*qrpile\*q
+pile : \*qlpile\*q | \*qcpile\*q | \*qrpile\*q | \*qpile\*q
pos : \*qover\*q | \*qsup\*q | \*qsub\*q | \*qto\*q | \*qfrom\*q
mark : \*qdot\*q | \*qdotdot\*q | \*qhat\*q | \*qtilde\*q | \*qvec\*q
| \*qdyad\*q | \*qbar\*q | \*qunder\*q
-font : \*qroman\*q | \*qitalic\*q | \*qbold\*q
+font : \*qroman\*q | \*qitalic\*q | \*qbold\*q | \*qfat\*q
list : eqn
| list \*qabove\*q eqn
space : [\e^~ \et]
The following control statements are available:
.Bl -tag -width Ds
.It Cm define
-Replace all occurances of a key with a value.
+Replace all occurrences of a key with a value.
Its syntax is as follows:
.Pp
.D1 define Ar key cvalc
.D1 define Ar foo cbar bazc
.Pp
It is an error to have an empty
-.Ar key or
+.Ar key
+or
.Ar val .
Note that a quoted
.Ar key
.Ed
.Pp
Self-referencing definitions will raise an error.
+The
+.Cm ndefine
+statement is a synonym for
+.Cm define ,
+while
+.Cm tdefine
+is discarded.
.It Cm gfont
Set the default font of subsequent output.
Its syntax is as follows:
and
.Ar val
are not expanded for replacements.
+This statement is a GNU extension.
.It Cm undef
Unset a previously-defined key.
Its syntax is as follows:
The
.Ar key
is not expanded for replacements.
+This statement is a GNU extension.
.El
.Sh COMPATIBILITY
This section documents the compatibility of mandoc
This
.Nm
reference was written by
-.An Kristaps Dzonsons Aq kristaps@bsd.lv .
+.An Kristaps Dzonsons Aq Mt kristaps@bsd.lv .