@marcr I believe that the “SD-” is for Software Download.
To verify, I just browsed to my.pega.com and selected software, searched for and then requested Pega GenAI Knowledge Buddy. This did create a new “SD-” request, here is the info related to same:
Thank you! Your request number is SD-xxxxxx
Your order includes products that require approval with expected turnaround time between 1-2 weeks. Once approved you will receive an email with instructions to download your order. Additionally if your request includes products that have prerequisites they will be listed below and added to your order.
If you haven’t received an email after 2 weeks, please contact Pega Support.