title: PayPal .Net library. Disallow certain credit card types during payment process
body: <p>After following <a href="https://developer.paypal.com/docs/api/quickstart/environment/" rel="nofollow noreferrer">this tutorial</a> on how to setup the PayPal payment process in my .Net application, one of the features that we want to implement is the ability to disallow certain credit card types like American Express or Discover cards.</p>
  <p>I can't find anything in the documentation on how to do this and googling around hasn't shown me anything either. Is this type of functionality possible? Or even legal?</p>