TODO.md in rake_factory-0.21.0 vs TODO.md in rake_factory-0.22.0.pre.1

@@ -1,2 +1,18 @@
 * Allow parameter reads to be memoized
 * More clearly distinguish between construction and runtime parameters
+  - Parameter types:
+    - definition-time parameter: must be set before definition of the task.
+    - invocation-time parameter: can be set before or after definition of the 
+      task; can be set in configuration block.
+  - Parameter value types:
+    - static value: do not depend on task set / task / runtime arguments.
+    - dynamic value: require task set / task / runtime arguments in order to be
+      resolved.
+  - For tasks:
+    - definition-time parameters can have static values and dynamic values of 
+      arity zero or one, optionally taking the task itself
+    - invocation-time parameters can have static values and dynamic values of 
+      arity zero, one or two, optionally taking the task itself and the runtime
+      arguments
+  - For task sets:
+    - all parameters are definition-time
\ No newline at end of file