1 files changed, 13 insertions, 2 deletions
diff --git a/eqn.7 b/eqn.7
index 85d80b91..ea05fdaf 100644
--- a/eqn.7
+++ b/eqn.7
@@ -30,11 +30,13 @@ and
 .Xr man 7
 .Ux
 manual pages.
-This manual describes the subset of the
+This manual describes the
 .Nm
 language accepted by the
 .Xr mandoc 1
-utility.
+utility, which correspond to the Second Edition eqn specification (see
+.Sx SEE ALSO
+for references).
 .Pp
 Equations within
 .Xr mdoc 7
@@ -66,6 +68,8 @@ eqn     : box | eqn box
 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
@@ -145,6 +149,13 @@ foo bar 'baz'
 .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: