title: Using Paypal REST C#
body: <p>I would like to use Paypal authenication service</p>
  
  <p><a href="https://www.paypal-labs.com/files/PayPal_Authentication_Service.pdf" rel="nofollow">https://www.paypal-labs.com/files/PayPal_Authentication_Service.pdf</a></p>
  
  <p>The document is however missing some information, </p>
  
  <pre><code>&lt;form method=post action=https://api-3tpaypal.com/nvp&gt; 
  &lt;input type=hidden name=USER value= API_username&gt; 
  &lt;input type=hidden name=PWD value= API_password&gt; 
  &lt;input type=hidden name=SIGNATURE value= API_signature&gt; 
  &lt;input type=hidden name=VERSION value=version&gt; 
  &lt;input type=hidden name=RETURNURL value=yourReturnURL&gt; 
  &lt;input type=hidden name=CANCELURL value=yourCancelURL&gt; 
  &lt;input type=hidden name=LOGOUTURL value=yourLogoutURL&gt; 
  &lt;input name=SERVICENAME1 value=Name&gt; 
  &lt;input name=SERVICEDEFREQ1 value=Required&gt; 
  &lt;input name=SERVICENAME2 value=Email&gt; 
  &lt;input name=SERVICEDEFREQ2 value=Required&gt; 
  &lt;input type=submit name=METHOD value=SetAuthFlowParam&gt; 
  &lt;/form&gt;
  </code></pre>
  
  <p>What VERSION? what is SERVICENAME1, SERVICEEDFREQ1?
   etc?</p>
  
  <p>REF: <a href="https://www.x.com/community/ppx/authentication" rel="nofollow">https://www.x.com/community/ppx/authentication</a></p>