title: Is it possible to POST advanced HTML variables for SUBSCRIBE buttons in the list of parameters submitted to PayPal?
body: <p>I'm using the PayPal standard SUBSCRIBE button.  The HTML looks something like the code-snippet below.  The issue is that it appears FORM parameters a1/p1/t1, a3/p3/t3, src/sra, and any other advanced HTML variables for the PayPal SUBSCRIBE button cannot be overridden.  That is, they remain set to the values you configured in the standard-button configuration on PayPal's website.</p>
  
  <p>QUESTION:  how can I programmatically override the advanced PayPal subscription parameters from my website?  Is this even possible?  Thanks.</p>
  
  <pre><code>&lt;form accept-charset="UTF-8" action="https://www.paypal.com/cgi-bin/webscr" class="signup_company" id="signup_company" method="post"&gt;
    &lt;input type="hidden" name="cmd" value="_s-xclick" /&gt;
    &lt;input type="hidden" name="hosted_button_id" value="MY_PAYPAL_BUTTON_ID" /&gt;
    &lt;input type="hidden" name="currency_code" value="USD" /&gt;
  
    &lt;!-- First two months of subscription are free. --&gt;
    &lt;input type="hidden" name="a1" value="0" /&gt;
    &lt;input type="hidden" name="p1" value="2" /&gt;
    &lt;input type="hidden" name="t1" value="M" /&gt;
  
    &lt;!-- Recurring subscription payments. --&gt;
    &lt;input type="hidden" name="a3" value="29.95" /&gt;
    &lt;input type="hidden" name="p3" value="1" /&gt;
    &lt;input type="hidden" name="t3" value="M" /&gt;
    &lt;input type="hidden" name="src" value="1" /&gt;
    &lt;input type="hidden" name="sra" value="1" /&gt;
  
    &lt;!-- Pass-through variable sent to paypal; it is set in javascript before the submit. --&gt;
    &lt;input type="hidden" name="custom" value="Evergreen::::foo@baz.com::::4" /&gt;
  
    &lt;input type="image" src="https://www.paypalobjects.com/en_US/i/btn/btn_subscribe_SM.gif"
      border="0" name="submit" alt="PayPal - The safer, easier way to pay online!"
      onclick="$(#signup_company).submit();" /&gt;
    &lt;img alt="" border="0" src="https://www.paypalobjects.com/en_US/i/scr/pixel.gif" width="1" height="1" /&gt;
  &lt;/form&gt;
  </code></pre>