Index: trunk/doc/developer/lihata_format/comm_concrete.lht
===================================================================
--- trunk/doc/developer/lihata_format/comm_concrete.lht	(revision 4292)
+++ trunk/doc/developer/lihata_format/comm_concrete.lht	(revision 4293)
@@ -14,10 +14,11 @@
 				type=li
 				desc { List of child objects }
 				li:children {
-					sy:line.ID    = {/lht_tree_doc/comm/line.ID}
-					sy:arc.ID     = {/lht_tree_doc/comm/arc.ID}
-					sy:polygon.ID = {/lht_tree_doc/comm/arc.ID}
-					ha:obj.ID     = { valtype=none;    desc={list of any concrete object }}
+					sy:line.ID       = {/lht_tree_doc/comm/line.ID}
+					sy:arc.ID        = {/lht_tree_doc/comm/arc.ID}
+					sy:polygon.ID    = {/lht_tree_doc/comm/polygon.ID}
+					sy:connection.ID = {/lht_tree_doc/comm/connection.ID}
+					ha:obj.ID        = { valtype=none;    desc={list of any concrete object }}
 				}
 			}
 			sy:attrib@dup   = {/lht_tree_doc/comm/attrib}
@@ -102,4 +103,18 @@
 		}
 	}
 
+	ha:connection.ID {
+		type=ha
+		desc { Logical object: connection between different groups }
+		li:children {
+			ha:conn {
+				type=li
+				desc { list of objects participating in the connection (at least 2)}
+				li:children {
+					ha:OIDPATH = { valtype=oidpath;   desc={drawing object making the connection )}}
+				}
+			}
+		}
+	}
+
 }}