Strange PHP tags
<p>I got the code below from a tutorial that teaches how to make wordpress plugins. It has some unusual PHP tags. For example,</p>

<p>a) 3rd line from the bottom, there is an opening <code>&lt;?php</code> tag. </p>

<p>b) And, also, after $base_map_url  is set, there is a closing <code>?&gt;</code> tag. </p>

<p>This is very different from what I've learned, yet the code works. </p>

<p>c) Also, in all the plugins the author has built, there is an opening <code>&lt;?php</code> tag at the very top but not a final closing one.</p>

<p>What is happening here, can you explain?</p>

<pre><code>&lt;?php
/*
 Plugin Name: Map plugin using shortcode
 Plugin URI: http://example
 Description: This plugin will get a map of whatever parameter is passed
 Author: Drew
 Version: 1.0
 Author URI: http://www.blah 
 */

function smp_map_it($addr)
{
    $addr = "1600 Pennsylvania Ave. Washington, D.C.";
    $base_map_url = 'http://maps.google.com/maps/api/staticmap?sensor=false&amp;size=256x256&amp;format=png&amp;center=';
    ?&gt;
    &lt;h2&gt;Your map:&lt;/h2&gt;
    &lt;img width="256" height="256"
        src="&lt;?php echo $base_map_url . urlencode($addr); ?&gt;" /&gt;
    &lt;?php 
}

add_shortcode('map-it','smp_map_it');
</code></pre>
