diff --git a/ideas.txt b/ideas.txt
index e3caffaf6..b7911ae18 100644
--- a/ideas.txt
+++ b/ideas.txt
@@ -1,6 +1,9 @@
 Real Parsing
   define grammar for command line
   implement flex/bison parser
+  new grammar includes:
+    - task delete <ID> [<ID> ...]
+    - task done <ID> [<ID> ...]
 
 User-Defined Reports
   report.xxx=id,project(2+),priority(1-),description
@@ -14,4 +17,51 @@ Test Suite
   debug=on to cause all cout to be csv
   regression tests for every bug, command, feature
 
+Recurrence
+  - new T::status recurring (stored as R)
+  - new user-specifiable attributes - recur:<duration> [until:<date>]
+  - duration:
+      daily, day, 1d
+      Nd
+      weekly, 1w
+      Nw
+      biweekly
+      monthly, 1m
+      bimonthly
+      Nm
+      quarterly, 1q
+      Nq
+      biannual, biyearly
+      annual, yearly, 1y
+      Na, Ny
+  - recur: without due:   => Error
+  - until: without recur: => Error
+  - New file format (version 3):  supports status R, recur:, until:, base:, range:
+  - on TDB.gc, adjust base: and compress range: for T::status == recurring
+  - all recurring tasks are removed from lists by T::*pendingT, and a synthetic
+    addendum is generated
+  - when a recurring task is completed, range: is updated, and a synthetic
+    task is added to completed.data that retains the attributes of the root
+
+  - Scenario:
+      # Today = 6/22/2008
+      % task add Friday due:6/15/2008 recur:weekly until 8/1/2008
+        # task must generate a base and range
+        # base:6/15/2008
+        # range:-------
+        #       ^6/15
+        #        ^6/22
+        #         ^6/29
+        #          ^7/6
+        #           ^7/13
+        #            ^7/20
+        #             ^7/27
+      % task ls
+      1 Friday 6/15/2008 .lte. today     (overdue)
+      2 Friday 6/22/2008 .lte. today     (due)
+      3 Friday 6/29/2008 one recurrence
+      4 Friday  7/6/2008                 (not shown)
+      5 Friday 7/13/2008                 (not shown)
+      6 Friday 7/20/2008                 (not shown)
+      7 Friday 7/27/2008                 (not shown)
 
diff --git a/src/parse.cpp b/src/parse.cpp
index 111921b35..8408ce535 100644
--- a/src/parse.cpp
+++ b/src/parse.cpp
@@ -107,6 +107,10 @@ static const char* attributes[] =
   "entry",
   "start",
   "end",
+  "recur",
+  "until",
+  "base",
+  "range",
   "",
 };
 
@@ -201,7 +205,7 @@ bool validDate (std::string& date, Config& conf)
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-static bool validPriority (std::string& input)
+static bool validPriority (const std::string& input)
 {
   if (input != "H" &&
       input != "M" &&
@@ -215,7 +219,10 @@ static bool validPriority (std::string& input)
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-static bool validAttribute (std::string& name, std::string& value, Config& conf)
+static bool validAttribute (
+  std::string& name,
+  std::string& value,
+  Config& conf)
 {
   guess ("attribute", attributes, name);
 
@@ -254,7 +261,7 @@ static bool validId (const std::string& input)
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-static bool validTag (std::string& input)
+static bool validTag (const std::string& input)
 {
   if ((input[0] == '-' || input[0] == '+') &&
        input.length () > 1)
@@ -310,6 +317,13 @@ static bool validSubstitution (
   return false;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool validDuration (const std::string& input)
+{
+  // TODO
+  return false;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Token        Distinguishing characteristic
 // -------      -----------------------------