diff --git a/openflow_input/standard-1.1 b/openflow_input/standard-1.1
index 9b72e8c..906519c 100644
--- a/openflow_input/standard-1.1
+++ b/openflow_input/standard-1.1
@@ -984,8 +984,44 @@
     uint8_t type == 15;
     uint16_t length;
     uint32_t xid;
-    uint16_t command;
-    uint8_t group_type;
+    enum ofp_group_mod_command command == ?;
+    enum ofp_group_type group_type;
+    pad(1);
+    uint32_t group_id;
+    list(of_bucket_t) buckets;
+};
+
+struct of_group_add : of_group_mod {
+    uint8_t version;
+    uint8_t type == 15;
+    uint16_t length;
+    uint32_t xid;
+    enum ofp_group_mod_command command == 0;
+    enum ofp_group_type group_type;
+    pad(1);
+    uint32_t group_id;
+    list(of_bucket_t) buckets;
+};
+
+struct of_group_modify : of_group_mod {
+    uint8_t version;
+    uint8_t type == 15;
+    uint16_t length;
+    uint32_t xid;
+    enum ofp_group_mod_command command == 1;
+    enum ofp_group_type group_type;
+    pad(1);
+    uint32_t group_id;
+    list(of_bucket_t) buckets;
+};
+
+struct of_group_delete : of_group_mod {
+    uint8_t version;
+    uint8_t type == 15;
+    uint16_t length;
+    uint32_t xid;
+    enum ofp_group_mod_command command == 2;
+    enum ofp_group_type group_type;
     pad(1);
     uint32_t group_id;
     list(of_bucket_t) buckets;
diff --git a/openflow_input/standard-1.2 b/openflow_input/standard-1.2
index e9d915a..9a48154 100644
--- a/openflow_input/standard-1.2
+++ b/openflow_input/standard-1.2
@@ -898,8 +898,44 @@
     uint8_t type == 15;
     uint16_t length;
     uint32_t xid;
-    uint16_t command;
-    uint8_t group_type;
+    enum ofp_group_mod_command command == ?;
+    enum ofp_group_type group_type;
+    pad(1);
+    uint32_t group_id;
+    list(of_bucket_t) buckets;
+};
+
+struct of_group_add : of_group_mod {
+    uint8_t version;
+    uint8_t type == 15;
+    uint16_t length;
+    uint32_t xid;
+    enum ofp_group_mod_command command == 0;
+    enum ofp_group_type group_type;
+    pad(1);
+    uint32_t group_id;
+    list(of_bucket_t) buckets;
+};
+
+struct of_group_modify : of_group_mod {
+    uint8_t version;
+    uint8_t type == 15;
+    uint16_t length;
+    uint32_t xid;
+    enum ofp_group_mod_command command == 1;
+    enum ofp_group_type group_type;
+    pad(1);
+    uint32_t group_id;
+    list(of_bucket_t) buckets;
+};
+
+struct of_group_delete : of_group_mod {
+    uint8_t version;
+    uint8_t type == 15;
+    uint16_t length;
+    uint32_t xid;
+    enum ofp_group_mod_command command == 2;
+    enum ofp_group_type group_type;
     pad(1);
     uint32_t group_id;
     list(of_bucket_t) buckets;
diff --git a/openflow_input/standard-1.3 b/openflow_input/standard-1.3
index db7ff0d..e7a1362 100644
--- a/openflow_input/standard-1.3
+++ b/openflow_input/standard-1.3
@@ -1058,8 +1058,44 @@
     uint8_t type == 15;
     uint16_t length;
     uint32_t xid;
-    uint16_t command;
-    uint8_t group_type;
+    enum ofp_group_mod_command command == ?;
+    enum ofp_group_type group_type;
+    pad(1);
+    uint32_t group_id;
+    list(of_bucket_t) buckets;
+};
+
+struct of_group_add : of_group_mod {
+    uint8_t version;
+    uint8_t type == 15;
+    uint16_t length;
+    uint32_t xid;
+    enum ofp_group_mod_command command == 0;
+    enum ofp_group_type group_type;
+    pad(1);
+    uint32_t group_id;
+    list(of_bucket_t) buckets;
+};
+
+struct of_group_modify : of_group_mod {
+    uint8_t version;
+    uint8_t type == 15;
+    uint16_t length;
+    uint32_t xid;
+    enum ofp_group_mod_command command == 1;
+    enum ofp_group_type group_type;
+    pad(1);
+    uint32_t group_id;
+    list(of_bucket_t) buckets;
+};
+
+struct of_group_delete : of_group_mod {
+    uint8_t version;
+    uint8_t type == 15;
+    uint16_t length;
+    uint32_t xid;
+    enum ofp_group_mod_command command == 2;
+    enum ofp_group_type group_type;
     pad(1);
     uint32_t group_id;
     list(of_bucket_t) buckets;