diff --git a/c/todo.txt b/c/todo.txt
index 435b439db..60f61c5cd 100644
--- a/c/todo.txt
+++ b/c/todo.txt
@@ -109,6 +109,62 @@ wolen:
     rs10041592 rs79177551  0.2  0.85
     rs10033329 rs4835294   0.2  0.46
 
+----------------------------------------------------------------
+
+explode across records by value (forward):
+implode across records by value (reverse):
+  mlr nest
+    --explode / --implode
+    --values
+    --records
+    --nested-fs semicolon
+
+  x=a;b;c,y=d
+
+  x=a,y=d
+  x=b,y=d
+  x=c,y=d
+
+explode across fields by value (forward):
+implode across fields by value (reverse):
+  mlr nest
+    --explode / --implode
+    --values
+    --fields
+    --nested-fs semicolon
+
+  x=a;b;c,y=d
+
+  x_1=a,x_2=b,x_3=cy=d
+
+explode across records by key-value (forward):
+implode across records by key-value (reverse):
+  mlr nest
+    --explode / --implode
+    --pairs
+    --records
+    --nested-ps colon
+    --nested-fs semicolon
+
+  x=a:1;b:2;c:3,y=d
+
+  a=1,y=d
+  b=2,y=d
+  c=3,y=d
+
+explode across fields by key-value (forward):
+implode across fields by key-value (reverse):
+  mlr nest
+    --explode / --implode
+    --pairs
+    --fields
+    --nested-ps colon
+    --nested-fs semicolon
+
+  x=a:1;b:2;c:3,y=d
+
+  a=1,b=2,c=3,y=d
+
 ================================================================
 TRI-SPLIT NULL