diff -pur mantis-1.0.8/core/email_api.php /var/www/mantis/core/email_api.php
--- mantis-1.0.8/core/email_api.php	2007-03-06 07:54:14.000000000 +0200
+++ /var/www/mantis/core/email_api.php	2007-07-05 17:55:49.000000000 +0300
@@ -17,6 +17,7 @@
 	require_once( $t_core_dir . 'custom_field_api.php' );
 	require_once( $t_core_dir . 'string_api.php' );
 	require_once( $t_core_dir . 'history_api.php' );
+	require_once( $t_core_dir . 'relationship_api.php' );
 	require_once( PHPMAILER_PATH . 'class.phpmailer.php' );
 
 	# reusable object of class SMTP
@@ -463,26 +464,11 @@
 	function email_relationship_added( $p_bug_id, $p_related_bug_id, $p_rel_type ) {
 		$t_opt = array();
 		$t_opt[] = bug_format_id( $p_related_bug_id );
-		switch ( $p_rel_type ) {
-			case BUG_BLOCKS:
-				email_generic( $p_bug_id, 'relation', 'email_notification_title_for_action_blocks_relationship_added', $t_opt );
-				break;
-			case BUG_DEPENDANT:
-				email_generic( $p_bug_id, 'relation', 'email_notification_title_for_action_dependant_on_relationship_added', $t_opt );
-				break;
-			case BUG_HAS_DUPLICATE:
-				email_generic( $p_bug_id, 'relation', 'email_notification_title_for_action_has_duplicate_relationship_added', $t_opt );
-				break;
-			case BUG_DUPLICATE:
-				email_generic( $p_bug_id, 'relation', 'email_notification_title_for_action_duplicate_of_relationship_added', $t_opt );
-				break;
-			case BUG_RELATED:
-				email_generic( $p_bug_id, 'relation', 'email_notification_title_for_action_related_to_relationship_added', $t_opt );
-				break;
-			default:
-				trigger_error( ERROR_RELATIONSHIP_NOT_FOUND, ERROR );
-				break;
-			}
+		global $g_relationships;
+		if ( !isset( $g_relationships[ $p_rel_type ] ) ) {
+			trigger_error( ERROR_RELATIONSHIP_NOT_FOUND, ERROR );
+		}
+		email_generic( $p_bug_id, 'relation', $g_relationships[ $p_rel_type ][ '#notify_added' ], $t_opt );
 	}
 
 	# --------------------
@@ -491,26 +477,11 @@
 	function email_relationship_deleted( $p_bug_id, $p_related_bug_id, $p_rel_type ) {
 		$t_opt = array();
 		$t_opt[] = bug_format_id( $p_related_bug_id );
-		switch ( $p_rel_type ) {
-			case BUG_BLOCKS:
-				email_generic( $p_bug_id, 'relation', 'email_notification_title_for_action_blocks_relationship_deleted', $t_opt );
-				break;
-			case BUG_DEPENDANT:
-				email_generic( $p_bug_id, 'relation', 'email_notification_title_for_action_dependant_on_relationship_deleted', $t_opt );
-				break;
-			case BUG_HAS_DUPLICATE:
-				email_generic( $p_bug_id, 'relation', 'email_notification_title_for_action_has_duplicate_relationship_deleted', $t_opt );
-				break;
-			case BUG_DUPLICATE:
-				email_generic( $p_bug_id, 'relation', 'email_notification_title_for_action_duplicate_of_relationship_deleted', $t_opt );
-				break;
-			case BUG_RELATED:
-				email_generic( $p_bug_id, 'relation', 'email_notification_title_for_action_related_to_relationship_deleted', $t_opt );
-				break;
-			default:
-				trigger_error( ERROR_RELATIONSHIP_NOT_FOUND, ERROR );
-				break;
-			}
+		global $g_relationships;
+		if ( !isset( $g_relationships[ $p_rel_type ] ) ) {
+			trigger_error( ERROR_RELATIONSHIP_NOT_FOUND, ERROR );
+		}
+		email_generic( $p_bug_id, 'relation', $g_relationships[ $p_rel_type ][ '#notify_deleted' ], $t_opt );
 	}
 
 	# --------------------
diff -pur mantis-1.0.8/core/relationship_api.php /var/www/mantis/core/relationship_api.php
--- mantis-1.0.8/core/relationship_api.php	2005-06-28 14:04:06.000000000 +0300
+++ /var/www/mantis/core/relationship_api.php	2007-07-05 19:06:56.000000000 +0300
@@ -67,43 +67,71 @@
 		var $dest_project_id;
 		var $type;
 	}
+	
+	$g_relationships = array();
+	$g_relationships[ BUG_DEPENDANT ] = array(
+	'#forward' => TRUE,
+	'#complementary' => BUG_BLOCKS,
+	'#description' => 'dependant_on',
+	'#notify_added' => 'email_notification_title_for_action_dependant_on_relationship_added',
+	'#notify_deleted' => 'email_notification_title_for_action_dependant_on_relationship_deleted',
+	'#edge_style' => array ('color' => '#C00000','dir' => 'back'),
+	);
+	$g_relationships[ BUG_BLOCKS ] = array(
+	'#forward' => FALSE,
+	'#complementary' => BUG_DEPENDANT,
+	'#description' => 'blocks',
+	'#notify_added' => 'email_notification_title_for_action_blocks_relationship_added',
+	'#notify_deleted' => 'email_notification_title_for_action_blocks_relationship_deleted',
+	'#edge_style' => array ('color' => '#C00000','dir' => 'forward'),
+	);
+	$g_relationships[ BUG_DUPLICATE ] = array(
+	'#forward' => TRUE,
+	'#complementary' => BUG_HAS_DUPLICATE,
+	'#description' => 'duplicate_of',
+	'#notify_added' => 'email_notification_title_for_action_duplicate_of_relationship_added',
+	'#notify_deleted' => 'email_notification_title_for_action_duplicate_of_relationship_deleted',
+	'#edge_style' => array ('style' => 'dashed','color' => '#808080'),
+	);
+	$g_relationships[ BUG_HAS_DUPLICATE ] = array(
+	'#forward' => FALSE,
+	'#complementary' => BUG_DUPLICATE,
+	'#description' => 'has_duplicate',
+	'#notify_added' => 'email_notification_title_for_action_has_duplicate_relationship_added',
+	'#notify_deleted' => 'email_notification_title_for_action_has_duplicate_relationship_deleted',
+	);
+	$g_relationships[ BUG_RELATED ] = array(
+	'#forward' => TRUE,
+	'#complementary' => BUG_RELATED,
+	'#description' => 'related_to',
+	'#notify_added' => 'email_notification_title_for_action_related_to_relationship_added',
+	'#notify_deleted' => 'email_notification_title_for_action_related_to_relationship_deleted',
+	);
+	if ( file_exists( dirname( dirname( __FILE__ ) ).DIRECTORY_SEPARATOR.'custom_relationships_inc.php' ) ) {
+		require_once( dirname( dirname( __FILE__ ) ).DIRECTORY_SEPARATOR.'custom_relationships_inc.php' );
+	}    
+
 
 	# --------------------
 	# Return the complementary type of the provided relationship
 	function relationship_get_complementary_type( $p_relationship_type ) {
-		switch ( $p_relationship_type ) {
-			case BUG_BLOCKS:
-				return BUG_DEPENDANT;
-				break;
-			case BUG_DEPENDANT:
-				return BUG_BLOCKS;
-				break;
-			case BUG_HAS_DUPLICATE:
-				return BUG_DUPLICATE;
-				break;
-			case BUG_DUPLICATE:
-				return BUG_HAS_DUPLICATE;
-				break;
-			case BUG_RELATED:
-				return BUG_RELATED;
-				break;
-			default:
-				trigger_error( ERROR_GENERIC, ERROR );
-				break;
+	        global $g_relationships;
+		if ( !isset( $g_relationships[ $p_relationship_type ] ) ) {
+			trigger_error( ERROR_GENERIC, ERROR );
 		}
+		return $g_relationships[ $p_relationship_type ][ '#complementary' ];
 	}
 
 	# --------------------
 	function relationship_add( $p_src_bug_id, $p_dest_bug_id, $p_relationship_type ) {
 		$t_mantis_bug_relationship_table = config_get( 'mantis_bug_relationship_table' );
 
-		if( $p_relationship_type == BUG_BLOCKS || $p_relationship_type == BUG_HAS_DUPLICATE ) {
-			# BUG_BLOCKS or BUG_HAS_DUPLICATE -> swap src and dest
+		global $g_relationships;
+		if ( $g_relationships[ $p_relationship_type ][ '#forward' ] === FALSE ) {
 			$c_src_bug_id = db_prepare_int( $p_dest_bug_id );
 			$c_dest_bug_id = db_prepare_int( $p_src_bug_id );
 			$c_relationship_type = db_prepare_int( relationship_get_complementary_type( $p_relationship_type ) );
-		}
-		else {
+		} else {
 			$c_src_bug_id = db_prepare_int( $p_src_bug_id );
 			$c_dest_bug_id = db_prepare_int( $p_dest_bug_id );
 			$c_relationship_type = db_prepare_int( $p_relationship_type );
@@ -129,13 +157,12 @@
 	function relationship_update( $p_relationship_id, $p_src_bug_id, $p_dest_bug_id, $p_relationship_type ) {
 		$t_mantis_bug_relationship_table = config_get( 'mantis_bug_relationship_table' );
 
-		if( $p_relationship_type == BUG_BLOCKS || $p_relationship_type == BUG_HAS_DUPLICATE ) {
-			# BUG_BLOCKS or BUG_HAS_DUPLICATE -> swap src and dest
+		global $g_relationships;
+		if ( $g_relationships[ $p_relationship_type ][ '#forward' ] === FALSE ) {
 			$c_src_bug_id = db_prepare_int( $p_dest_bug_id );
 			$c_dest_bug_id = db_prepare_int( $p_src_bug_id );
 			$c_relationship_type = db_prepare_int( relationship_get_complementary_type( $p_relationship_type ) );
-		}
-		else {
+		} else {
 			$c_src_bug_id = db_prepare_int( $p_src_bug_id );
 			$c_dest_bug_id = db_prepare_int( $p_dest_bug_id );
 			$c_relationship_type = db_prepare_int( $p_relationship_type );
@@ -412,61 +439,28 @@
 	# --------------------
 	# get class description of a relationship (source side)
 	function relationship_get_description_src_side( $p_relationship_type ) {
-		switch ( $p_relationship_type ) {
-			case BUG_DUPLICATE:
-				return lang_get( 'duplicate_of' );
-				break;
-			case BUG_RELATED:
-				return lang_get( 'related_to' ) ;
-				break;
-			case BUG_DEPENDANT:
-				return lang_get( 'dependant_on' ) ;
-				break;
-			default:
-				trigger_error( ERROR_RELATIONSHIP_NOT_FOUND, ERROR );
+		global $g_relationships;
+		if ( !isset( $g_relationships[ $p_relationship_type ] ) ) {
+			trigger_error( ERROR_RELATIONSHIP_NOT_FOUND, ERROR );
 		}
+		return lang_get( $g_relationships[ $p_relationship_type ][ '#description' ] ); 
 	}
 
 	# --------------------
 	# get class description of a relationship (destination side)
 	function relationship_get_description_dest_side( $p_relationship_type ) {
-		switch ( $p_relationship_type ) {
-			case BUG_DUPLICATE:
-				return lang_get( 'has_duplicate' ) ;
-				break;
-			case BUG_RELATED:
-				return lang_get( 'related_to' ) ;
-				break;
-			case BUG_DEPENDANT:
-				return lang_get( 'blocks' ) ;
-				break;
-			default:
-				trigger_error( ERROR_RELATIONSHIP_NOT_FOUND, ERROR );
+		global $g_relationships;
+		if ( !isset( $g_relationships[ $p_relationship_type ] ) ||
+		     !isset( $g_relationships[ $g_relationships[ $p_relationship_type ][ '#complementary' ] ] ) ) {
+			trigger_error( ERROR_RELATIONSHIP_NOT_FOUND, ERROR );
 		}
+		return lang_get( $g_relationships[ $g_relationships[ $p_relationship_type ][ '#complementary' ] ][ '#description' ] ); 
 	}
 
 	# --------------------
 	# get class description of a relationship as it's stored in the history
 	function relationship_get_description_for_history( $p_relationship_code ) {
-		switch ( $p_relationship_code ) {
-			case BUG_HAS_DUPLICATE:
-				return lang_get( 'has_duplicate' ) ;
-				break;
-			case BUG_DUPLICATE:
-				return lang_get( 'duplicate_of' );
-				break;
-			case BUG_BLOCKS:
-				return lang_get( 'blocks' ) ;
-				break;
-			case BUG_DEPENDANT:
-				return lang_get( 'dependant_on' ) ;
-				break;
-			case BUG_RELATED:
-				return lang_get( 'related_to' ) ;
-				break;
-			default:
-				trigger_error( ERROR_RELATIONSHIP_NOT_FOUND, ERROR );
-		}
+		return relationship_get_description_src_side( $p_relationship_code );
 	}
 
 	# --------------------
@@ -683,6 +677,7 @@
  	# --------------------
  	# print HTML relationship listbox
 	function relationship_list_box( $p_default_rel_type = -1, $p_select_name = "rel_type", $p_include_any = false) {
+		global $g_relationships;
 ?>
 <select name="<?php echo $p_select_name?>">
 <?php if ($p_include_any) { ?>
@@ -690,24 +685,11 @@
 <?php
     }
 ?>
-<option value="<?php echo BUG_RELATED ?>"<?php echo ( $p_default_rel_type == BUG_RELATED ? ' selected' : '' ) ?>><?php echo lang_get( 'related_to' ) ?></option>
-<option value="<?php echo BUG_DEPENDANT ?>"<?php echo ( $p_default_rel_type == BUG_DEPENDANT ? ' selected' : '' ) ?>><?php echo lang_get( 'dependant_on' ) ?></option>
-<option value="<?php echo BUG_BLOCKS ?>" <?php echo ( $p_default_rel_type == BUG_BLOCKS ? ' selected' : '' ) ?>><?php echo lang_get( 'blocks' ) ?></option>
-<option value="<?php echo BUG_DUPLICATE ?>"<?php echo ( $p_default_rel_type == BUG_DUPLICATE ? ' selected' : '' ) ?>><?php echo lang_get( 'duplicate_of' ) ?></option>
-<option value="<?php echo BUG_HAS_DUPLICATE ?>"<?php echo ( $p_default_rel_type == BUG_HAS_DUPLICATE ? ' selected' : '' ) ?>><?php echo lang_get( 'has_duplicate' ) ?></option>
-</select>
+<?php foreach ( $g_relationships as $type => $relationship ) { ?>
+<option value="<?php echo $type ?>"<?php echo ( $p_default_rel_type == $type ? ' selected' : '' ) ?>><?php echo lang_get( $relationship['#description'] ) ?></option>
 <?php
-	}
-
- 	# --------------------
- 	# print HTML relationship listbox
-	function relationship_list_box_for_cloned_bug( $p_default_rel_type = -1 ) {
+    }
 ?>
-<select name="rel_type">
-<option value="-1"<?php echo ( $p_default_rel_type == -1 ? ' selected' : '' ) ?>><?php echo lang_get( 'no_relationship' ) ?></option>
-<option value="<?php echo BUG_RELATED ?>"<?php echo ( $p_default_rel_type == BUG_RELATED ? ' selected' : '' ) ?>><?php echo lang_get( 'related_to' ) ?></option>
-<option value="<?php echo BUG_DEPENDANT ?>"<?php echo ( $p_default_rel_type == BUG_DEPENDANT ? ' selected' : '' ) ?>><?php echo lang_get( 'dependant_on' ) ?></option>
-<option value="<?php echo BUG_BLOCKS ?>" <?php echo ( $p_default_rel_type == BUG_BLOCKS ? ' selected' : '' ) ?>><?php echo lang_get( 'blocks' ) ?></option>
 </select>
 <?php
 	}
diff -pur mantis-1.0.8/core/relationship_graph_api.php /var/www/mantis/core/relationship_graph_api.php
--- mantis-1.0.8/core/relationship_graph_api.php	2005-04-22 23:34:04.000000000 +0200
+++ /var/www/mantis/core/relationship_graph_api.php	2007-07-05 19:05:25.000000000 +0300
@@ -157,32 +157,12 @@
 
 					$t_related_id	= bug_format_id( $t_dst );
 
-					switch ( $t_relation ) {
-						case BUG_DUPLICATE:
-							$t_edge_style = array (
-								'style' => 'dashed',
-								'color' => '#808080'
-							);
-							break;
-
-						case BUG_DEPENDANT:
-							$t_edge_style = array (
-								'color' => '#C00000',
-								'dir' => 'back'
-							);
-							break;
-
-						case BUG_BLOCKS:
-							$t_edge_style = array (
-								'color' => '#C00000',
-								'dir' => 'forward'
-							);
-							break;
-
-						default:
-							$t_edge_style = array ( );
-							break;
-					}
+          global $g_relationships;
+          if (isset($g_relationships[ $t_relation ])) {
+            $t_edge_style = $g_relationships[ $t_relation ][ '#edge_style' ];
+          } else {
+            $t_edge_style = array ( );
+          }
 
 					$t_graph->add_edge( $t_id_string, $t_related_id, $t_edge_style );
 				}