If it can help someone, in source code you can see all direction of navigation and the history actions while navigating views ! (line 633 : ionic-angular.js)
// history actions while navigating views
var ACTION_INITIAL_VIEW = 'initialView';
var ACTION_NEW_VIEW = 'newView';
var ACTION_MOVE_BACK = 'moveBack';
var ACTION_MOVE_FORWARD = 'moveForward';
// direction of navigation
var DIRECTION_BACK = 'back';
var DIRECTION_FORWARD = 'forward';
var DIRECTION_ENTER = 'enter';
var DIRECTION_EXIT = 'exit';
var DIRECTION_SWAP = 'swap';
var DIRECTION_NONE = 'none';