gistfile1.txt

/* the lines of code that generates ALL checkbox fields*/ 
						  case 'checkbox':
						   echo '<input type="checkbox" name="'.$field['id'].'" class="'.$field['id'].'" id="'.$field['id'].'" ',$meta ? ' checked="checked"' : '','/>
						           <label for="'.$field['id'].'">'.$field['desc'].'</label>';
						   break;
						   


/* the actual HTML output seems the same */ 

<tr>
	 <th><label for="custom_multiday">Multi-Day</label></th>
	 <td><input type="checkbox" name="custom_multiday" class="custom_multiday" id="custom_multiday" checked="checked">
						           <label for="custom_multiday"></label></td></tr>
						           
<tr><!-- only this field actually saves the OFF status -->
	  <th><label for="custom_recurring">Recurring</label></th>
	  <td><input type="checkbox" name="custom_recurring" class="custom_recurring" id="custom_recurring" checked="checked">
						           <label for="custom_recurring"></label></td></tr>
						           
<tr> 
	   <th><label for="custom_cost_free">Free Admission? </label></th>
	   <td><input type="checkbox" name="custom_cost_free" class="custom_cost_free" id="custom_cost_free" checked="checked">
						           <label for="custom_cost_free">Check box if admission if free</label></td></tr>			
						           
						           
						           
						           
/* code for the saving (truncated)  */ 

    // loop through fields and save the data
    foreach ($custom_meta_fields as $field) {   

if(isset($_POST[$field['id']])){
	$old = get_post_meta($post_id, $field['id'], true);
	$new = $_POST[$field['id']];
	if ($new && $new != $old) {
	
			update_post_meta($post_id, $field['id'], $new);
	        } elseif ('' == $new && $old) {
	            delete_post_meta($post_id, $field['id'], $old);
	        }
 }elseif(!isset($_POST[$field['id']])){
                          // this deletes the value if the field has nothing in it. 
	          	            delete_post_meta($post_id, $field['id'], $old);
	          	
	          }// end if isset 
	            } // end foreach