Filter: named limits

1 files changed, 13 insertions, 0 deletions

diff --git a/README.md b/README.md
index 3c3dd10..776ec90 100644
--- a/README.md
+++ b/README.md
@@ -221,6 +221,19 @@ the enclosing object. For [filters](#filter), the default behavior is
 to apply the limit for each source address separately. For [logging
 classes](#log), the limit is considered absolute by default.
 
+The packet rates contributing to the limit may be summed over multiple
+[filters](#filter). This can be achieved by setting the optional
+**name** attribute to equal values among the related limits. Named
+limits may be specific only to fixed-size blocks of either the source
+or the destination address, not both. However, the address to be
+considered may vary among the rules using the limit and may be
+selected by setting an attribute named **addr** to either **src**
+(default) or **dest**. By default, all bits of the selected address
+are taken into account, but address family–specific prefix
+lengths can be set via the top-level **limit** dictionary, where the
+keys correspond to limit names and values follow the syntax of
+**src-mask** and **dest-mask**.
+
 ### <a name="log"></a>Logging Classes
 
 A *logging class* specifies how packets matching certain rules are