As you know, the content of those three boxes in the lower left can be customized through the normal Navi settings menu. So if you're still using the original text elements etc then you can just change the context through the settings as per the manual.
If you've replaced the original elements with your own and you need the actual internal variables to display what you want, then have a look in data.zip\ui_pioneer\common\ui\navigatemap.ui and down towards the bottom you will find all the variables for the various options for those three lines.