diff --git a/design2.txt b/design2.txt
new file mode 100644
index 0000000..99fe9ed
--- /dev/null
+++ b/design2.txt
@@ -0,0 +1,29 @@
+function after_place_node(pos, node)
+    # [s1][f1]----[n1] x [n2]-----[f2][s2]
+    # s..secondary, f..far, n..near
+    res,dir1,dir2 = update_nears(pos, node)
+    if res:
+        local fpos1,fdir1 = del_meta(pos, dir1) or repair_tube(pos, dir1) or pos,Turn180[dir1] 
+        local fpos2,fdir2 = del_meta(pos, dir2) or repair_tube(pos, dir2) or pos,Turn180[dir2]
+        add_meta(fpos1, fpos2,fdir2)
+        add_meta(fpos2, fpos1,fdir1)
+                           -- pos        , data
+        update_secondary_node(fpos1,fdir1, fpos2,fdir2)
+        update_secondary_node(fpos2,fdir2, fpos1,fdir1)
+            if mt.nodes[node.name].tubelib2 then mt.nodes[node.name].tl2(pos, dir):
+                
+               
+function after_dig_node(pos, oldnode):
+    # [s1][f1]----[n1] x [n2]-----[f2][s2]
+    # s..secondary, f..far, n..near
+    res,dir1,dir2 = update_nears(pos, oldnode)
+    if res:
+        local fpos1,fdir1 = repair_tube(pos, dir1) or pos,Turn180[dir1] 
+        local fpos2,fdir2 = repair_tube(pos, dir2) or pos,Turn180[dir2]
+        local npos1,ndir1 = get_pos(pos, dir1),Turn180[dir1]
+        local npos2,ndir2 = get_pos(pos, dir2),Turn180[dir2]
+        add_meta(fpos1, npos1,ndir1)
+        add_meta(fpos2, npos1,ndir1)
+                           -- pos        , data
+        update_secondary_node(fpos1,fdir1, npos1,ndir1)
+        update_secondary_node(fpos2,fdir2, npos2,ndir2)