@Bill - "IgniteNA" is the promo code you would enter on the payment page, similar to a coupon code you enter when shopping online. During step 3 of the checkout process, you will see "enter voucher or promo code," above where you enter credit card information.
One additional note: Be sure to select "Microsoft Ignite North America 2015" as the testing center location when scheduling your exam. You'll see the test center location is only "open" from May 4 to May 8, 2015. Hope this helps!
Great conversation, Blain and Ed! Love what Ed said about the difference between getting an MCSE and being an MCSE. I also enjoyed your take on upgrade exams, as many IT pros are now wondering whether they should complete their MCITP and take 417, or just go to 410/411/412.
Again, thanks for this episode. I'll share it with our Microsoft Learning community!