    deferred class
    	EV_MODEL

    General
    	cluster: interface
    	description:
    		"Every figure has a center. The position of the
    		center are the values x and y. It is the position
    		on the screen. The center of the figure can be moved arround
    		and the figure can be rotated around its center and
    		scaled in x and y direction. 2*pi is a full rotation. The
    		direction of a rotation is clockwise."

    Ancestors
    	EV_ABSTRACT_PICK_AND_DROPABLE*
    	EV_MODEL_DOUBLE_MATH
    	HASHABLE*

    Action sequences
    	conforming_pick_actions: EV_NOTIFY_ACTION_SEQUENCE
    	drop_actions: EV_PND_ACTION_SEQUENCE
    	pick_actions: EV_PND_START_ACTION_SEQUENCE
    	pointer_button_press_actions: EV_POINTER_BUTTON_ACTION_SEQUENCE
    	pointer_button_release_actions: EV_POINTER_BUTTON_ACTION_SEQUENCE
    	pointer_double_press_actions: EV_POINTER_BUTTON_ACTION_SEQUENCE
    	pointer_enter_actions: EV_NOTIFY_ACTION_SEQUENCE
    	pointer_leave_actions: EV_NOTIFY_ACTION_SEQUENCE
    	pointer_motion_actions: EV_POINTER_MOTION_ACTION_SEQUENCE

    Queries
    	accept_cursor: EV_POINTER_STYLE
    	angle: REAL_64
    	are_events_sended_to_group: BOOLEAN
    	bounding_box: EV_RECTANGLE
    	deny_cursor: EV_POINTER_STYLE
    	group: EV_MODEL_GROUP
    	has_capture: BOOLEAN
    	id: INTEGER_32
    	id_object (an_id: INTEGER_32): IDENTIFIED
    	is_center_valid: BOOLEAN
    	is_hashable: BOOLEAN
    	is_in_group: BOOLEAN
    	is_in_world: BOOLEAN
    	is_rotatable: BOOLEAN
    	is_scalable: BOOLEAN
    	is_sensitive: BOOLEAN
    	is_show_requested: BOOLEAN
    	is_transformable: BOOLEAN
    	object_id: INTEGER_32
    	pebble: ANY
    	pebble_function: FUNCTION [ANY, TUPLE, ANY]
    	point_count: INTEGER_32
    	pointer_style: EV_POINTER_STYLE
    	position_on_figure (a_x, a_y: INTEGER_32): BOOLEAN
    	target_name: STRING_GENERAL
    	world: EV_MODEL_WORLD
    	x: INTEGER_32
    	y: INTEGER_32

    Commands
    	center_invalidate
    	disable_capture
    	disable_events_sended_to_group
    	disable_sensitive
    	enable_capture
    	enable_events_sended_to_group
    	enable_sensitive
    	hide
    	remove_pebble
    	rotate (an_angle: REAL_64)
    	rotate_around (an_angle: REAL_64; ax, ay: INTEGER_32)
    	scale (a_scale: REAL_64)
    	scale_abs (a_scale: REAL_64)
    	scale_x (a_scale_x: REAL_64)
    	scale_x_abs (a_scale_x: REAL_64)
    	scale_y (a_scale_y: REAL_64)
    	scale_y_abs (a_scale_y: REAL_64)
    	set_accept_cursor (a_cursor: EV_POINTER_STYLE)
    	set_deny_cursor (a_cursor: EV_POINTER_STYLE)
    	set_pebble (a_pebble: [like pebble] ANY)
    	set_pebble_function (a_function: FUNCTION [ANY, TUPLE, ANY])
    	set_pointer_style (a_cursor: [like pointer_style] EV_POINTER_STYLE)
    	set_target_name (a_name: STRING_GENERAL)
    	set_x (a_x: INTEGER_32)
    	set_x_y (a_x, a_y: INTEGER_32)
    	set_y (a_y: INTEGER_32)
    	show
    	transform (a_transformation: EV_MODEL_TRANSFORMATION)

    Constraints
    	point array exists
    	center exists
    	x is center x
    	y is center y
    	all points exist
    	projection matrix not void
    	is transfomable implies rotatable and scalable