Index: cck_time.module
===================================================================
--- cck_time.module	(revision 123)
+++ cck_time.module	(working copy)
@@ -90,6 +90,7 @@
           break;
       }
       // hours
+      $hours[-1] = '--';
       for ($i = $h_min; $i <= $h_max; $i++) {
         if ($clock == 24) {
           $val = ($i < 10) ? "0$i" : $i;
@@ -101,6 +102,7 @@
       }
 
       // minutes
+      $minutes[-1] = '--';
       for ($i = 0; $i <= 59; $i+=$increment) {
         $val = ($i < 10) ? "0$i" : $i;
         $minutes[$val] = $val;
@@ -134,7 +136,7 @@
         $form[$field['field_name']]['meridem'] = array(
           '#type' => 'select',
           '#title' => '',
-          '#options' => array('AM'=>'AM', 'PM'=>'PM'),
+          '#options' => array(-1 => '--', 'AM'=>'AM', 'PM'=>'PM'),
           '#required' => $field['required'],
           '#default_value' => $node_field['default_meridiem'],
           '#prefix' => '<div class="cck-time-element">',
@@ -155,16 +157,21 @@
           $h_max = 23;
           break;
       }
-      if (!is_numeric($node_field['hour']) || $node_field['hour'] < $h_min || $node_field['hour'] > $h_max ) {
+      if (!$field['required'] && $node_field['hour'] == -1 && $node_field['minute'] == -1 && $node_field['meridem'] == -1) {
+        // this is ok, the time is empty and it's not a required field
+      }
+      else {
+        if (!is_numeric($node_field['hour']) || $node_field['hour'] < $h_min || $node_field['hour'] > $h_max ) {
           form_set_error($field['field_name'], t('Please select an hour from the list.'));
-      }
-      if (!is_numeric($node_field['minute']) || $node_field['minute'] < 0 || $node_field['minute'] > 59 ) {
+        }
+        if (!is_numeric($node_field['minute']) || $node_field['minute'] < 0 || $node_field['minute'] > 59 ) {
           form_set_error($field['field_name'], t('Please select a minute from the list.'));
-      }
-      if ($clock == 12) {
-        if ($node_field['meridem'] != 'AM' && $node_field['meridem'] != 'PM') {
-          form_set_error($field['field_name'], t('Please select AM or PM.'));
         }
+        if ($clock == 12) {
+          if ($node_field['meridem'] != 'AM' && $node_field['meridem'] != 'PM') {
+            form_set_error($field['field_name'], t('Please select AM or PM.'));
+          }
+        }
       }
       break;
 
@@ -173,6 +180,10 @@
       if ($clock == 12) {
         $node_field[0]['value'] .= $node_field['meridem'];
       }
+      // blank out for all -1s
+      if ($node_field['hour'] == -1 && $node_field['minute'] == -1 && $node_field['meridem'] == -1) {
+        $node_field[0]['value'] = '';
+      }
       break;
 
   }