function _loadMBTA() {
    /*
    This script adds "MBTA map" as a choice on Google Maps. (The "official"
    current choices are Map and Satellite.)
 
    Basically, this happens by accessing the _m.map.mapTypes JavaScript
    variable, which is a list of map-spec objects. Each map-spec object defines
    how the particular map is displayed. This script creates a custom map-spec
    object, appends it to that list and refreshes the "toggle links," which is
    the section of the Google Maps interface that allows a user to switch
    between map views.
    */
 
    function copy_obj(o) { var c = new Object(); for (var e in o) { c[e] = o[e]; } return c; }
 
    // Google Maps conveniently provides the default map-spec objects as
    // non-obfuscated variables. Rather than redefining the entire map-spec
    // interface, just copy _GOOGLE_MAP_SPEC as a starting point. And doing
    // "var cta = _GOOGLE_MAP_SPEC" won't work, because JavaScript copies by
    // reference. If you wanted to use the satellite map as a starting point,
    // you'd use _KEYHOLE_SPEC here.
    var mbta = copy_obj(_GOOGLE_MAP_SPEC);
 
    // Google Maps will request the tiled map images from the following URL.
    // This (obviously) is a custom server-side script that I've set up.
    // Ideally the images themselves would be embedded within this Greasemonkey
    // script, so my server doesn't get pounded (and users maintain privacy).
    mbta.baseURL="http://maps.mojodna.net/mbta/?";
 
    // This adds the small, red "New!" text. :-)
    mbta.isNew = true;
 
    // This is the map's display name.
    mbta.getLinkText = function() { return 'MBTA map'; }
 
    // This is a hard-coded limit on how far a user can zoom out. If it's set
    // to 1, only the farthest-in zoom will work, etc. Because this script
    // currently works only on zoom level 4, setting this wouldn't be helpful.
    // cta.numZoomLevels = 1;
 
    // Register the new map spec.
    _m.map.mapTypes[_m.map.mapTypes.length] = mbta;
 
    // (Slightly dirty.) Refresh the display that allows a user to switch
    // between views.
    document.getElementById('toggle').innerHTML = '';
    _m.map.createSpecToggleLinks(document.getElementById('toggle'));
}