Be more specific about `Dv', `Er', and `Ev'.

1 files changed, 18 insertions, 4 deletions

diff --git a/mdoc.7 b/mdoc.7
index 2669d66e..717e6637 100644
--- a/mdoc.7
+++ b/mdoc.7
@@ -1691,14 +1691,21 @@ See also
 and
 .Sx \&Os .
 .Ss \&Dv
-Defined variables such as preprocessor constants.
+Defined variables such as preprocessor constants, constant symbols,
+enumeration values, and so on.
 .Pp
 Examples:
+.Dl \&.Dv NULL
 .Dl \&.Dv BUFSIZ
 .Dl \&.Dv STDOUT_FILENO
 .Pp
 See also
-.Sx \&Er .
+.Sx \&Er
+and
+.Sx \&Ev
+for special-purpose constants and
+.Sx \&Va
+for variable symbols.
 .Ss \&Dx
 Format the DragonFly BSD version provided as an argument, or a default
 value if no argument is provided.
@@ -1774,14 +1781,17 @@ argument is used as the enclosure head, for example, specifying \e(lq
 will emulate
 .Sx \&Do .
 .Ss \&Er
-Display error constants.
+Error constants for definitions of the
+.Va errno
+libc global variable.
 .Pp
 Examples:
 .Dl \&.Er EPERM
 .Dl \&.Er ENOENT
 .Pp
 See also
-.Sx \&Dv .
+.Sx \&Dv
+for general constants.
 .Ss \&Es
 This macro is obsolete and not implemented.
 .Ss \&Ev
@@ -1791,6 +1801,10 @@ Environmental variables such as those specified in
 Examples:
 .Dl \&.Ev DISPLAY
 .Dl \&.Ev PATH
+.Pp
+See also
+.Sx \&Dv
+for general constants.
 .Ss \&Ex
 Insert a standard sentence regarding exit values.
 Its syntax is as follows: