diff --git a/src/Context.cpp b/src/Context.cpp
index 57a687a5d..c21af7f61 100644
--- a/src/Context.cpp
+++ b/src/Context.cpp
@@ -113,12 +113,17 @@ void Context::initialize (int argc, const char** argv)
   // Instantiate built-in command objects.
   Command::factory (commands);
 
+  // Instantiate built-in column objects.
+  Column::factory (columns);
+
   // Finally categorize all arguments.
   args.categorize ();
 
   // TODO Instantiate extension command objects.
   // TODO Instantiate default command object.
 
+  // TODO Instantiate extension column objects.
+
   // TODO Instantiate extension UDA objects.
   // TODO Instantiate extension format objects.
 
diff --git a/src/Context.h b/src/Context.h
index b3e08518c..def6ba196 100644
--- a/src/Context.h
+++ b/src/Context.h
@@ -106,6 +106,7 @@ public:
 */
 
   std::map <std::string, Command*>    commands;
+  std::map <std::string, Column*>     columns;
 
   int                                 terminal_width;
   int                                 terminal_height;
diff --git a/src/columns/ColDate.cpp b/src/columns/ColDate.cpp
index 4884dc887..86cca1425 100644
--- a/src/columns/ColDate.cpp
+++ b/src/columns/ColDate.cpp
@@ -41,10 +41,10 @@ extern Context context;
 ////////////////////////////////////////////////////////////////////////////////
 ColumnDate::ColumnDate ()
 {
+  _name      = "";
   _type      = "date";
   _style     = "default";
   _label     = "";
-  _attribute = "";
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -52,15 +52,21 @@ ColumnDate::~ColumnDate ()
 {
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool ColumnDate::validate (std::string& value)
+{
+  return true;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Set the minimum and maximum widths for the value.
 void ColumnDate::measure (Task& task, int& minimum, int& maximum)
 {
   minimum = maximum = 0;
 
-  if (task.has (_attribute))
+  if (task.has (_name))
   {
-    Date date ((time_t) strtol (task.get (_attribute).c_str (), NULL, 10));
+    Date date ((time_t) strtol (task.get (_name).c_str (), NULL, 10));
 
     if (_style == "default")
     {
@@ -96,7 +102,7 @@ void ColumnDate::measure (Task& task, int& minimum, int& maximum)
       minimum = maximum = Duration (now - date).formatCompact ().length ();
     }
     else
-      throw format (STRING_COLUMN_BAD_FORMAT, _attribute, _style);
+      throw format (STRING_COLUMN_BAD_FORMAT, _name, _style);
   }
 }
 
@@ -107,7 +113,7 @@ void ColumnDate::render (
   int width,
   Color& color)
 {
-  if (task.has (_attribute))
+  if (task.has (_name))
   {
     if (_style == "default")
     {
@@ -124,12 +130,12 @@ void ColumnDate::render (
       lines.push_back (
         color.colorize (
           leftJustify (
-            Date ((time_t) strtol (task.get (_attribute).c_str (), NULL, 10))
+            Date ((time_t) strtol (task.get (_name).c_str (), NULL, 10))
               .toString (format), width)));
     }
     else if (_style == "julian")
     {
-      double julian = (Date ((time_t) strtol (task.get (_attribute).c_str (), NULL, 10))
+      double julian = (Date ((time_t) strtol (task.get (_name).c_str (), NULL, 10))
         .toEpoch () / 86400.0) + 2440587.5;
 
       lines.push_back (
@@ -142,7 +148,7 @@ void ColumnDate::render (
       lines.push_back (
         color.colorize (
           rightJustify (
-            Date ((time_t) strtol (task.get (_attribute).c_str (), NULL, 10))
+            Date ((time_t) strtol (task.get (_name).c_str (), NULL, 10))
               .toEpochString (), width)));
     }
     else if (_style == "iso")
@@ -150,12 +156,12 @@ void ColumnDate::render (
       lines.push_back (
         color.colorize (
           leftJustify (
-            Date ((time_t) strtol (task.get (_attribute).c_str (), NULL, 10))
+            Date ((time_t) strtol (task.get (_name).c_str (), NULL, 10))
               .toISO (), width)));
     }
     else if (_style == "age")
     {
-      Date date ((time_t) strtol (task.get (_attribute).c_str (), NULL, 10));
+      Date date ((time_t) strtol (task.get (_name).c_str (), NULL, 10));
       Date now;
 
       lines.push_back (
diff --git a/src/columns/ColDate.h b/src/columns/ColDate.h
index 7a943d3ca..dafc2b897 100644
--- a/src/columns/ColDate.h
+++ b/src/columns/ColDate.h
@@ -40,11 +40,9 @@ public:
   ColumnDate ();
   ~ColumnDate ();
 
+  virtual bool validate (std::string&);
   virtual void measure (Task&, int&, int&);
   virtual void render (std::vector <std::string>&, Task&, int, Color&);
-
-protected:
-  std::string _attribute;
 };
 
 #endif
diff --git a/src/columns/ColDepends.cpp b/src/columns/ColDepends.cpp
index d35eea841..7d589d538 100644
--- a/src/columns/ColDepends.cpp
+++ b/src/columns/ColDepends.cpp
@@ -39,6 +39,7 @@ extern Context context;
 ////////////////////////////////////////////////////////////////////////////////
 ColumnDepends::ColumnDepends ()
 {
+  _name  = "depends";
   _type  = "string";
   _style = "default";
   _label = STRING_COLUMN_LABEL_DEP;
@@ -49,6 +50,12 @@ ColumnDepends::~ColumnDepends ()
 {
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool ColumnDepends::validate (std::string& value)
+{
+  return true;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Overriden so that style <----> label are linked.
 // Note that you can not determine which gets called first.
@@ -93,7 +100,7 @@ void ColumnDepends::measure (Task& task, int& minimum, int& maximum)
     }
   }
   else
-    throw format (STRING_COLUMN_BAD_FORMAT, "depends", _style);
+    throw format (STRING_COLUMN_BAD_FORMAT, _name, _style);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -103,7 +110,7 @@ void ColumnDepends::render (
   int width,
   Color& color)
 {
-  if (task.has ("depends"))
+  if (task.has (_name))
   {
     if (_style == "indicator")
     {
diff --git a/src/columns/ColDepends.h b/src/columns/ColDepends.h
index d70a3389a..925ae218b 100644
--- a/src/columns/ColDepends.h
+++ b/src/columns/ColDepends.h
@@ -40,6 +40,7 @@ public:
   ColumnDepends ();
   ~ColumnDepends ();
 
+  bool validate (std::string&);
   void setStyle (const std::string&);
   void measure (Task&, int&, int&);
   void render (std::vector <std::string>&, Task&, int, Color&);
diff --git a/src/columns/ColDescription.cpp b/src/columns/ColDescription.cpp
index a88d1cfca..519d66cc8 100644
--- a/src/columns/ColDescription.cpp
+++ b/src/columns/ColDescription.cpp
@@ -40,6 +40,7 @@ extern Context context;
 ////////////////////////////////////////////////////////////////////////////////
 ColumnDescription::ColumnDescription ()
 {
+  _name  = "description";
   _type  = "string";
   _style = "default";
   _label = STRING_COLUMN_LABEL_DESC;
@@ -50,11 +51,17 @@ ColumnDescription::~ColumnDescription ()
 {
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool ColumnDescription::validate (std::string& value)
+{
+  return true;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Set the minimum and maximum widths for the value.
 void ColumnDescription::measure (Task& task, int& minimum, int& maximum)
 {
-  std::string description = task.get ("description");
+  std::string description = task.get (_name);
 
   // The text
   // <indent> <date> <anno>
@@ -127,7 +134,7 @@ void ColumnDescription::measure (Task& task, int& minimum, int& maximum)
   }
 
   else
-    throw format (STRING_COLUMN_BAD_FORMAT, "description.", _style);
+    throw format (STRING_COLUMN_BAD_FORMAT, _name, _style);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -137,7 +144,7 @@ void ColumnDescription::render (
   int width,
   Color& color)
 {
-  std::string description = task.get ("description");
+  std::string description = task.get (_name);
 
   // This is a description
   // <date> <anno>
diff --git a/src/columns/ColDescription.h b/src/columns/ColDescription.h
index c6c5f5795..bd68c7a5f 100644
--- a/src/columns/ColDescription.h
+++ b/src/columns/ColDescription.h
@@ -40,6 +40,7 @@ public:
   ColumnDescription ();
   ~ColumnDescription ();
 
+  bool validate (std::string&);
   void measure (Task&, int&, int&);
   void render (std::vector <std::string>&, Task&, int, Color&);
 
diff --git a/src/columns/ColDue.cpp b/src/columns/ColDue.cpp
index 46a2dade1..943bbfcea 100644
--- a/src/columns/ColDue.cpp
+++ b/src/columns/ColDue.cpp
@@ -40,8 +40,8 @@ extern Context context;
 ////////////////////////////////////////////////////////////////////////////////
 ColumnDue::ColumnDue ()
 {
+  _name      = "due";
   _label     = STRING_COLUMN_LABEL_DUE;
-  _attribute = "due";
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -49,6 +49,12 @@ ColumnDue::~ColumnDue ()
 {
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool ColumnDue::validate (std::string& value)
+{
+  return ColumnDate::validate (value);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Overriden so that style <----> label are linked.
 // Note that you can not determine which gets called first.
@@ -66,11 +72,11 @@ void ColumnDue::measure (Task& task, int& minimum, int& maximum)
 {
   minimum = maximum = 0;
 
-  if (task.has (_attribute))
+  if (task.has (_name))
   {
     if (_style == "countdown")
     {
-      Date date ((time_t) strtol (task.get (_attribute).c_str (), NULL, 10));
+      Date date ((time_t) strtol (task.get (_name).c_str (), NULL, 10));
       Date now;
       minimum = maximum = Duration (now - date).format ().length ();
     }
@@ -86,11 +92,11 @@ void ColumnDue::render (
   int width,
   Color& color)
 {
-  if (task.has (_attribute))
+  if (task.has (_name))
   {
     if (_style == "countdown")
     {
-      Date date ((time_t) strtol (task.get (_attribute).c_str (), NULL, 10));
+      Date date ((time_t) strtol (task.get (_name).c_str (), NULL, 10));
       Date now;
 
       lines.push_back (
diff --git a/src/columns/ColDue.h b/src/columns/ColDue.h
index 508d2db45..9c4b5b995 100644
--- a/src/columns/ColDue.h
+++ b/src/columns/ColDue.h
@@ -36,6 +36,7 @@ public:
   ColumnDue ();
   ~ColumnDue ();
 
+  bool validate (std::string&);
   void setStyle (const std::string&);
   void measure (Task&, int&, int&);
   void render (std::vector <std::string>&, Task&, int, Color&);
diff --git a/src/columns/ColEnd.cpp b/src/columns/ColEnd.cpp
index cd9bcde5c..388847b9f 100644
--- a/src/columns/ColEnd.cpp
+++ b/src/columns/ColEnd.cpp
@@ -33,8 +33,8 @@
 ////////////////////////////////////////////////////////////////////////////////
 ColumnEnd::ColumnEnd ()
 {
+  _name      = "end";
   _label     = STRING_COLUMN_LABEL_COMPLETE;
-  _attribute = "end";
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -43,3 +43,9 @@ ColumnEnd::~ColumnEnd ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+bool ColumnEnd::validate (std::string& value)
+{
+  return ColumnDate::validate (value);
+}
+
+////////////////////////////////////////////////////////////////////////////////
diff --git a/src/columns/ColEnd.h b/src/columns/ColEnd.h
index c360b2a51..146a2570b 100644
--- a/src/columns/ColEnd.h
+++ b/src/columns/ColEnd.h
@@ -35,6 +35,8 @@ class ColumnEnd : public ColumnDate
 public:
   ColumnEnd ();
   ~ColumnEnd ();
+
+  bool validate (std::string&);
 };
 
 #endif
diff --git a/src/columns/ColEntry.cpp b/src/columns/ColEntry.cpp
index 166c1a2dd..04f8f8712 100644
--- a/src/columns/ColEntry.cpp
+++ b/src/columns/ColEntry.cpp
@@ -33,8 +33,8 @@
 ////////////////////////////////////////////////////////////////////////////////
 ColumnEntry::ColumnEntry ()
 {
+  _name      = "entry";
   _label     = STRING_COLUMN_LABEL_ADDED;
-  _attribute = "entry";
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -42,6 +42,12 @@ ColumnEntry::~ColumnEntry ()
 {
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool ColumnEntry::validate (std::string& value)
+{
+  return ColumnDate::validate (value);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Overriden so that style <----> label are linked.
 // Note that you can not determine which gets called first.
diff --git a/src/columns/ColEntry.h b/src/columns/ColEntry.h
index 1f3382822..3545a9d5c 100644
--- a/src/columns/ColEntry.h
+++ b/src/columns/ColEntry.h
@@ -36,6 +36,7 @@ public:
   ColumnEntry ();
   ~ColumnEntry ();
 
+  bool validate (std::string&);
   void setStyle (const std::string&);
 };
 
diff --git a/src/columns/ColID.cpp b/src/columns/ColID.cpp
index e8186686d..f9790c443 100644
--- a/src/columns/ColID.cpp
+++ b/src/columns/ColID.cpp
@@ -38,6 +38,7 @@ extern Context context;
 ////////////////////////////////////////////////////////////////////////////////
 ColumnID::ColumnID ()
 {
+  _name  = "id";
   _type  = "number";
   _style = "default";
   _label = STRING_COLUMN_LABEL_ID;
@@ -48,6 +49,12 @@ ColumnID::~ColumnID ()
 {
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool ColumnID::validate (std::string& value)
+{
+  return true;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Set the minimum and maximum widths for the value.
 void ColumnID::measure (Task& task, int& minimum, int& maximum)
@@ -63,7 +70,7 @@ void ColumnID::measure (Task& task, int& minimum, int& maximum)
   minimum = maximum = length;
 
   if (_style != "default")
-    throw format (STRING_COLUMN_BAD_FORMAT, "id", _style);
+    throw format (STRING_COLUMN_BAD_FORMAT, _name, _style);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/src/columns/ColID.h b/src/columns/ColID.h
index ab42eb920..d6a4ca9f2 100644
--- a/src/columns/ColID.h
+++ b/src/columns/ColID.h
@@ -40,6 +40,7 @@ public:
   ColumnID ();
   ~ColumnID ();
 
+  bool validate (std::string&);
   void measure (Task&, int&, int&);
   void render (std::vector <std::string>&, Task&, int, Color&);
 
diff --git a/src/columns/ColPriority.cpp b/src/columns/ColPriority.cpp
index 07fc91da1..44236b49d 100644
--- a/src/columns/ColPriority.cpp
+++ b/src/columns/ColPriority.cpp
@@ -37,6 +37,7 @@ extern Context context;
 ////////////////////////////////////////////////////////////////////////////////
 ColumnPriority::ColumnPriority ()
 {
+  _name  = "priority";
   _type  = "string";
   _style = "default";
   _label = STRING_COLUMN_LABEL_PRI;
@@ -47,6 +48,20 @@ ColumnPriority::~ColumnPriority ()
 {
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool ColumnPriority::validate (std::string& value)
+{
+  value = upperCase (value);
+
+  if (value == "H" ||
+      value == "M" ||
+      value == "L" ||
+      value == "")
+    return true;
+
+  return false;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Overriden so that style <----> label are linked.
 // Note that you can not determine which gets called first.
@@ -62,7 +77,7 @@ void ColumnPriority::setStyle (const std::string& value)
 // Set the minimum and maximum widths for the value.
 void ColumnPriority::measure (Task& task, int& minimum, int& maximum)
 {
-  std::string priority = task.get ("priority");
+  std::string priority = task.get (_name);
 
   minimum = maximum = 1;
   if (_style == "long")
@@ -82,7 +97,7 @@ void ColumnPriority::render (
   int width,
   Color& color)
 {
-  std::string priority = task.get ("priority");
+  std::string priority = task.get (_name);
   if (_style == "long")
   {
          if (priority == "H") priority = "High";
diff --git a/src/columns/ColPriority.h b/src/columns/ColPriority.h
index f5ecfd1bd..a0a0f288f 100644
--- a/src/columns/ColPriority.h
+++ b/src/columns/ColPriority.h
@@ -40,6 +40,7 @@ public:
   ColumnPriority ();
   ~ColumnPriority ();
 
+  bool validate (std::string&);
   void setStyle (const std::string&);
   void measure (Task&, int&, int&);
   void render (std::vector <std::string>&, Task&, int, Color&);
diff --git a/src/columns/ColProject.cpp b/src/columns/ColProject.cpp
index a73e75d7f..1a479909d 100644
--- a/src/columns/ColProject.cpp
+++ b/src/columns/ColProject.cpp
@@ -37,6 +37,7 @@ extern Context context;
 ////////////////////////////////////////////////////////////////////////////////
 ColumnProject::ColumnProject ()
 {
+  _name  = "project";
   _type  = "string";
   _style = "default";
   _label = STRING_COLUMN_LABEL_PROJECT;
@@ -47,11 +48,17 @@ ColumnProject::~ColumnProject ()
 {
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool ColumnProject::validate (std::string& value)
+{
+  return true;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Set the minimum and maximum widths for the value.
 void ColumnProject::measure (Task& task, int& minimum, int& maximum)
 {
-  std::string project = task.get ("project");
+  std::string project = task.get (_name);
 
   if (_style == "parent")
   {
@@ -60,7 +67,7 @@ void ColumnProject::measure (Task& task, int& minimum, int& maximum)
       project = project.substr (0, period);
   }
   else if (_style != "default")
-    throw format (STRING_COLUMN_BAD_FORMAT, "project.", _style);
+    throw format (STRING_COLUMN_BAD_FORMAT, _name, _style);
 
   minimum = longestWord (project);
   maximum = project.length ();
@@ -73,7 +80,7 @@ void ColumnProject::render (
   int width,
   Color& color)
 {
-  std::string project = task.get ("project");
+  std::string project = task.get (_name);
   if (_style == "parent")
   {
     std::string::size_type period = project.find ('.');
diff --git a/src/columns/ColProject.h b/src/columns/ColProject.h
index fb08fbb81..461b12a5c 100644
--- a/src/columns/ColProject.h
+++ b/src/columns/ColProject.h
@@ -40,6 +40,7 @@ public:
   ColumnProject ();
   ~ColumnProject ();
 
+  bool validate (std::string&);
   void measure (Task&, int&, int&);
   void render (std::vector <std::string>&, Task&, int, Color&);
 
diff --git a/src/columns/ColRecur.cpp b/src/columns/ColRecur.cpp
index a473af3cd..f1edffaf9 100644
--- a/src/columns/ColRecur.cpp
+++ b/src/columns/ColRecur.cpp
@@ -37,6 +37,7 @@ extern Context context;
 ////////////////////////////////////////////////////////////////////////////////
 ColumnRecur::ColumnRecur ()
 {
+  _name  = "recur";
   _type  = "string";
   _style = "default";
   _label = STRING_COLUMN_LABEL_RECUR;
@@ -47,6 +48,12 @@ ColumnRecur::~ColumnRecur ()
 {
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool ColumnRecur::validate (std::string& value)
+{
+  return true;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Overriden so that style <----> label are linked.
 // Note that you can not determine which gets called first.
@@ -68,11 +75,11 @@ void ColumnRecur::measure (Task& task, int& minimum, int& maximum)
   }
   else if (_style == "indicator")
   {
-    if (task.has ("recur"))
+    if (task.has (_name))
       minimum = maximum = context.config.get ("recurrence.indicator").length ();
   }
   else
-    throw format (STRING_COLUMN_BAD_FORMAT, "recur.", _style);
+    throw format (STRING_COLUMN_BAD_FORMAT, _name, _style);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -88,7 +95,7 @@ void ColumnRecur::render (
   }
   else if (_style == "indicator")
   {
-    if (task.has ("recur"))
+    if (task.has (_name))
       lines.push_back (
         color.colorize (
           rightJustify (context.config.get ("recurrence.indicator"), width)));
diff --git a/src/columns/ColRecur.h b/src/columns/ColRecur.h
index 7f3c7fd70..12de48373 100644
--- a/src/columns/ColRecur.h
+++ b/src/columns/ColRecur.h
@@ -40,6 +40,7 @@ public:
   ColumnRecur ();
   ~ColumnRecur ();
 
+  bool validate (std::string&);
   void setStyle (const std::string&);
   void measure (Task&, int&, int&);
   void render (std::vector <std::string>&, Task&, int, Color&);
diff --git a/src/columns/ColStart.cpp b/src/columns/ColStart.cpp
index c82628095..d6f1ba702 100644
--- a/src/columns/ColStart.cpp
+++ b/src/columns/ColStart.cpp
@@ -37,8 +37,8 @@ extern Context context;
 ////////////////////////////////////////////////////////////////////////////////
 ColumnStart::ColumnStart ()
 {
-  _label     = STRING_COLUMN_LABEL_STARTED;
-  _attribute = "start";
+  _name  = "start";
+  _label = STRING_COLUMN_LABEL_STARTED;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -46,6 +46,12 @@ ColumnStart::~ColumnStart ()
 {
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool ColumnStart::validate (std::string& value)
+{
+  return ColumnDate::validate (value);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Overriden so that style <----> label are linked.
 // Note that you can not determine which gets called first.
@@ -63,7 +69,7 @@ void ColumnStart::measure (Task& task, int& minimum, int& maximum)
 {
   minimum = maximum = 0;
 
-  if (task.has (_attribute))
+  if (task.has (_name))
   {
     if (_style == "active")
     {
@@ -82,7 +88,7 @@ void ColumnStart::render (
   int width,
   Color& color)
 {
-  if (task.has (_attribute))
+  if (task.has (_name))
   {
     if (_style == "active")
     {
diff --git a/src/columns/ColStart.h b/src/columns/ColStart.h
index 9e59a111a..98903cf01 100644
--- a/src/columns/ColStart.h
+++ b/src/columns/ColStart.h
@@ -36,6 +36,7 @@ public:
   ColumnStart ();
   ~ColumnStart ();
 
+  bool validate (std::string&);
   void setStyle (const std::string&);
   void measure (Task&, int&, int&);
   void render (std::vector <std::string>&, Task&, int, Color&);
diff --git a/src/columns/ColStatus.cpp b/src/columns/ColStatus.cpp
index 3a0e46bb5..af97cd01c 100644
--- a/src/columns/ColStatus.cpp
+++ b/src/columns/ColStatus.cpp
@@ -37,6 +37,7 @@ extern Context context;
 ////////////////////////////////////////////////////////////////////////////////
 ColumnStatus::ColumnStatus ()
 {
+  _name  = "status";
   _type  = "string";
   _style = "default";
   _label = STRING_COLUMN_LABEL_STATUS;
@@ -47,6 +48,12 @@ ColumnStatus::~ColumnStatus ()
 {
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool ColumnStatus::validate (std::string& value)
+{
+  return true;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Overriden so that style <----> label are linked.
 // Note that you can not determine which gets called first.
@@ -81,7 +88,7 @@ void ColumnStatus::measure (Task& task, int& minimum, int& maximum)
   else if (_style == "short")
     minimum = maximum = 1;
   else
-    throw format (STRING_COLUMN_BAD_FORMAT, "status.", _style);
+    throw format (STRING_COLUMN_BAD_FORMAT, _name, _style);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/src/columns/ColStatus.h b/src/columns/ColStatus.h
index cc2368870..82207faf6 100644
--- a/src/columns/ColStatus.h
+++ b/src/columns/ColStatus.h
@@ -40,6 +40,7 @@ public:
   ColumnStatus ();
   ~ColumnStatus ();
 
+  bool validate (std::string&);
   void setStyle (const std::string&);
   void measure (Task&, int&, int&);
   void render (std::vector <std::string>&, Task&, int, Color&);
diff --git a/src/columns/ColString.cpp b/src/columns/ColString.cpp
index adb264d95..ea8166a04 100644
--- a/src/columns/ColString.cpp
+++ b/src/columns/ColString.cpp
@@ -1,4 +1,4 @@
-////////////////////////////////////////////////////////////////////////////////
+///////////////////////////////////////////////////////////////////////////////
 // taskwarrior - a command line task list manager.
 //
 // Copyright 2006 - 2011, Paul Beckingham, Federico Hernandez.
@@ -37,6 +37,7 @@ extern Context context;
 ////////////////////////////////////////////////////////////////////////////////
 ColumnString::ColumnString ()
 {
+  _name  = "string";
   _type  = "string";
   _style = "default";
   _label = "";
@@ -72,7 +73,7 @@ void ColumnString::measure (const std::string& value, int& minimum, int& maximum
            _style == "right_fixed")
     minimum = maximum = strippedLength (value);
   else
-    throw format (STRING_COLUMN_BAD_FORMAT, "string.", _style);
+    throw format (STRING_COLUMN_BAD_FORMAT, _name, _style);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/src/columns/ColTags.cpp b/src/columns/ColTags.cpp
index c7aa97024..7f4405007 100644
--- a/src/columns/ColTags.cpp
+++ b/src/columns/ColTags.cpp
@@ -38,6 +38,7 @@ extern Context context;
 ////////////////////////////////////////////////////////////////////////////////
 ColumnTags::ColumnTags ()
 {
+  _name  = "tags";
   _type  = "string";
   _style = "default";
   _label = STRING_COLUMN_LABEL_TAGS;
@@ -48,6 +49,12 @@ ColumnTags::~ColumnTags ()
 {
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool ColumnTags::validate (std::string& value)
+{
+  return true;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Overriden so that style <----> label are linked.
 // Note that you can not determine which gets called first.
@@ -73,7 +80,7 @@ void ColumnTags::measure (Task& task, int& minimum, int& maximum)
   else if (_style == "count")     minimum = maximum = 3;
   else if (_style == "default")
   {
-    std::string tags = task.get ("tags");
+    std::string tags = task.get (_name);
     minimum = 0;
     maximum = tags.length ();
 
@@ -88,7 +95,7 @@ void ColumnTags::measure (Task& task, int& minimum, int& maximum)
     }
   }
   else
-    throw format (STRING_COLUMN_BAD_FORMAT, "tags.", _style);
+    throw format (STRING_COLUMN_BAD_FORMAT, _name, _style);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -98,7 +105,7 @@ void ColumnTags::render (
   int width,
   Color& color)
 {
-  std::string tags = task.get ("tags");
+  std::string tags = task.get (_name);
   if (tags != "")
   {
     if (_style == "indicator")
diff --git a/src/columns/ColTags.h b/src/columns/ColTags.h
index 9b83ab976..7c4180b0e 100644
--- a/src/columns/ColTags.h
+++ b/src/columns/ColTags.h
@@ -40,6 +40,7 @@ public:
   ColumnTags ();
   ~ColumnTags ();
 
+  bool validate (std::string&);
   void setStyle (const std::string&);
   void measure (Task&, int&, int&);
   void render (std::vector <std::string>&, Task&, int, Color&);
diff --git a/src/columns/ColUUID.cpp b/src/columns/ColUUID.cpp
index 35e8dacd2..bd3c1a7a2 100644
--- a/src/columns/ColUUID.cpp
+++ b/src/columns/ColUUID.cpp
@@ -38,6 +38,7 @@ extern Context context;
 ////////////////////////////////////////////////////////////////////////////////
 ColumnUUID::ColumnUUID ()
 {
+  _name  = "uuid";
   _type  = "string";
   _style = "default";
   _label = STRING_COLUMN_LABEL_UUID;
@@ -48,6 +49,12 @@ ColumnUUID::~ColumnUUID ()
 {
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool ColumnUUID::validate (std::string& value)
+{
+  return true;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Set the minimum and maximum widths for the value.
 void ColumnUUID::measure (Task&, int& minimum, int& maximum)
@@ -55,7 +62,7 @@ void ColumnUUID::measure (Task&, int& minimum, int& maximum)
        if (_style == "default") minimum = maximum = 36;
   else if (_style == "short")   minimum = maximum = 8;
   else
-    throw format (STRING_COLUMN_BAD_FORMAT, "uuid.", _style);
+    throw format (STRING_COLUMN_BAD_FORMAT, _name, _style);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -68,10 +75,10 @@ void ColumnUUID::render (
   // f30cb9c3-3fc0-483f-bfb2-3bf134f00694  default
   //                             34f00694  short
   if (_style == "default")
-    lines.push_back (color.colorize (leftJustify (task.get ("uuid"), width)));
+    lines.push_back (color.colorize (leftJustify (task.get (_name), width)));
 
   else if (_style == "short")
-    lines.push_back (color.colorize (leftJustify (task.get ("uuid").substr (28), width)));
+    lines.push_back (color.colorize (leftJustify (task.get (_name).substr (28), width)));
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/src/columns/ColUUID.h b/src/columns/ColUUID.h
index 2d6934f25..5507e49e1 100644
--- a/src/columns/ColUUID.h
+++ b/src/columns/ColUUID.h
@@ -40,6 +40,7 @@ public:
   ColumnUUID ();
   ~ColumnUUID ();
 
+  bool validate (std::string&);
   void measure (Task&, int&, int&);
   void render (std::vector <std::string>&, Task&, int, Color&);
 
diff --git a/src/columns/ColUntil.cpp b/src/columns/ColUntil.cpp
index 177ead8c1..743f1d327 100644
--- a/src/columns/ColUntil.cpp
+++ b/src/columns/ColUntil.cpp
@@ -33,8 +33,8 @@
 ////////////////////////////////////////////////////////////////////////////////
 ColumnUntil::ColumnUntil ()
 {
+  _name      = "until";
   _label     = STRING_COLUMN_LABEL_UNTIL;
-  _attribute = "until";
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -43,3 +43,9 @@ ColumnUntil::~ColumnUntil ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+bool ColumnUntil::validate (std::string& value)
+{
+  return ColumnDate::validate (value);
+}
+
+////////////////////////////////////////////////////////////////////////////////
diff --git a/src/columns/ColUntil.h b/src/columns/ColUntil.h
index fcb06c062..56065ed9f 100644
--- a/src/columns/ColUntil.h
+++ b/src/columns/ColUntil.h
@@ -35,6 +35,8 @@ class ColumnUntil : public ColumnDate
 public:
   ColumnUntil ();
   ~ColumnUntil ();
+
+  bool validate (std::string&);
 };
 
 #endif
diff --git a/src/columns/ColUrgency.cpp b/src/columns/ColUrgency.cpp
index 64b2337f0..8d0870416 100644
--- a/src/columns/ColUrgency.cpp
+++ b/src/columns/ColUrgency.cpp
@@ -37,6 +37,7 @@ extern Context context;
 ////////////////////////////////////////////////////////////////////////////////
 ColumnUrgency::ColumnUrgency ()
 {
+  _name  = "urgency";
   _type  = "number";
   _style = "default";
   _label = STRING_COLUMN_LABEL_URGENCY;
@@ -54,7 +55,7 @@ void ColumnUrgency::measure (Task& task, int& minimum, int& maximum)
   minimum = maximum = format (task.urgency (), 4, 3).length ();
 
   if (_style != "default")
-    throw format (STRING_COLUMN_BAD_FORMAT, "urgency.", _style);
+    throw format (STRING_COLUMN_BAD_FORMAT, _name, _style);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/src/columns/ColWait.cpp b/src/columns/ColWait.cpp
index 44460bf13..e7f915519 100644
--- a/src/columns/ColWait.cpp
+++ b/src/columns/ColWait.cpp
@@ -33,8 +33,8 @@
 ////////////////////////////////////////////////////////////////////////////////
 ColumnWait::ColumnWait ()
 {
+  _name      = "wait";
   _label     = STRING_COLUMN_LABEL_WAIT;
-  _attribute = "wait";
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -43,3 +43,9 @@ ColumnWait::~ColumnWait ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+bool ColumnWait::validate (std::string& value)
+{
+  return ColumnDate::validate (value);
+}
+
+////////////////////////////////////////////////////////////////////////////////
diff --git a/src/columns/ColWait.h b/src/columns/ColWait.h
index 93510b6fe..b1a9ecdf2 100644
--- a/src/columns/ColWait.h
+++ b/src/columns/ColWait.h
@@ -35,6 +35,8 @@ class ColumnWait : public ColumnDate
 public:
   ColumnWait ();
   ~ColumnWait ();
+
+  bool validate (std::string&);
 };
 
 #endif
diff --git a/src/columns/Column.cpp b/src/columns/Column.cpp
index c26b49e4e..2acfa1beb 100644
--- a/src/columns/Column.cpp
+++ b/src/columns/Column.cpp
@@ -52,7 +52,7 @@
 extern Context context;
 
 ////////////////////////////////////////////////////////////////////////////////
-// Supports the new complete column definition:
+// Supports the complete column definition:
 //
 //   <type>[.<format>]
 //
@@ -73,37 +73,62 @@ Column* Column::factory (const std::string& name, const std::string& report)
     column_style = "default";
   }
 
-  Column* column;
-       if (column_name == "depends")     column = new ColumnDepends ();
-  else if (column_name == "description") column = new ColumnDescription ();
-  else if (column_name == "due")         column = new ColumnDue ();
-  else if (column_name == "end")         column = new ColumnEnd ();
-  else if (column_name == "entry")       column = new ColumnEntry ();
-  else if (column_name == "id")          column = new ColumnID ();
-  else if (column_name == "priority")    column = new ColumnPriority ();
-  else if (column_name == "project")     column = new ColumnProject ();
-  else if (column_name == "recur")       column = new ColumnRecur ();
-  else if (column_name == "start")       column = new ColumnStart ();
-  else if (column_name == "status")      column = new ColumnStatus ();
-  else if (column_name == "tags")        column = new ColumnTags ();
-  else if (column_name == "until")       column = new ColumnUntil ();
-  else if (column_name == "urgency")     column = new ColumnUrgency ();
-  else if (column_name == "uuid")        column = new ColumnUUID ();
-  else if (column_name == "wait")        column = new ColumnWait ();
+  Column* c;
+       if (column_name == "depends")     c = new ColumnDepends ();
+  else if (column_name == "description") c = new ColumnDescription ();
+  else if (column_name == "due")         c = new ColumnDue ();
+  else if (column_name == "end")         c = new ColumnEnd ();
+  else if (column_name == "entry")       c = new ColumnEntry ();
+  else if (column_name == "id")          c = new ColumnID ();
+  else if (column_name == "priority")    c = new ColumnPriority ();
+  else if (column_name == "project")     c = new ColumnProject ();
+  else if (column_name == "recur")       c = new ColumnRecur ();
+  else if (column_name == "start")       c = new ColumnStart ();
+  else if (column_name == "status")      c = new ColumnStatus ();
+  else if (column_name == "tags")        c = new ColumnTags ();
+  else if (column_name == "until")       c = new ColumnUntil ();
+  else if (column_name == "urgency")     c = new ColumnUrgency ();
+  else if (column_name == "uuid")        c = new ColumnUUID ();
+  else if (column_name == "wait")        c = new ColumnWait ();
 
-  // Special non-task column
-  else if (column_name == "string")      column = new ColumnString ();
+  // Special non-task column.
+  else if (column_name == "string")      c = new ColumnString ();
   else
     throw format (STRING_COLUMN_BAD_NAME, column_name);
 
-  column->setReport (report);
-  column->setStyle (column_style);
-  return column;
+  c->setReport (report);
+  c->setStyle (column_style);
+  return c;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Bulk column instantiation.
+void Column::factory (std::map <std::string, Column*>& all)
+{
+  Column* c;
+
+  c = new ColumnDepends ();        all[c->_name] = c;
+  c = new ColumnDescription ();    all[c->_name] = c;
+  c = new ColumnDue ();            all[c->_name] = c;
+  c = new ColumnEnd ();            all[c->_name] = c;
+  c = new ColumnEntry ();          all[c->_name] = c;
+  c = new ColumnID ();             all[c->_name] = c;
+  c = new ColumnPriority ();       all[c->_name] = c;
+  c = new ColumnProject ();        all[c->_name] = c;
+  c = new ColumnRecur ();          all[c->_name] = c;
+  c = new ColumnStart ();          all[c->_name] = c;
+  c = new ColumnStatus ();         all[c->_name] = c;
+  c = new ColumnTags ();           all[c->_name] = c;
+  c = new ColumnUntil ();          all[c->_name] = c;
+  c = new ColumnUrgency ();        all[c->_name] = c;
+  c = new ColumnUUID ();           all[c->_name] = c;
+  c = new ColumnWait ();           all[c->_name] = c;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 Column::Column ()
-: _type ("string")
+: _name ("")
+, _type ("string")
 , _style ("default")
 , _label ("")
 , _report ("")
@@ -113,9 +138,11 @@ Column::Column ()
 ////////////////////////////////////////////////////////////////////////////////
 Column::Column (const Column& other)
 {
+  _name  = other._name;
   _type  = other._type;
   _style = other._style;
   _label = other._label;
+  _label = other._report;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -123,9 +150,11 @@ Column& Column::operator= (const Column& other)
 {
   if (this != &other)
   {
+    _name    = other._name;
     _type    = other._type;
     _style   = other._style;
     _label   = other._label;
+    _report  = other._report;
   }
 
   return *this;
@@ -134,8 +163,9 @@ Column& Column::operator= (const Column& other)
 ////////////////////////////////////////////////////////////////////////////////
 bool Column::operator== (const Column& other) const
 {
-  return _type  == other._type   &&
-         _style == other._style   &&
+  return _name  == other._name  &&
+         _type  == other._type  &&
+         _style == other._style &&
          _label == other._label;
 }
 
@@ -176,6 +206,12 @@ void Column::renderHeader (
   }
 }
 
+////////////////////////////////////////////////////////////////////////////////
+bool Column::validate (std::string& input)
+{
+  return input.length () ? true : false;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // No L10N.
 void Column::measure (const std::string&, int&, int&)
diff --git a/src/columns/Column.h b/src/columns/Column.h
index 692a6f48c..832fba0d7 100644
--- a/src/columns/Column.h
+++ b/src/columns/Column.h
@@ -37,6 +37,7 @@ class Column
 {
 public:
   static Column* factory (const std::string&, const std::string&);
+  static void factory (std::map <std::string, Column*>&);
 
   Column ();
   Column (const Column&);
@@ -52,6 +53,7 @@ public:
   virtual void setLabel  (const std::string& value) { _label = value;  }
   virtual void setReport (const std::string& value) { _report = value; }
 
+  virtual bool validate (std::string&);
   virtual void measure (const std::string&, int&, int&);
   virtual void measure (Task&, int&, int&);
   virtual void renderHeader (std::vector <std::string>&, int, Color&);
@@ -59,6 +61,7 @@ public:
   virtual void render (std::vector <std::string>&, Task&, int, Color&);
 
 protected:
+  std::string _name;
   std::string _type;
   std::string _style;
   std::string _label;