What are the different types of promotion scrolls (I see ones that start with R, with L, with D, T, etc.)?

Sir, P Scrolls typically have vacancy promotion packets for O-3, O-4 and O-5 on them. S scrolls are for ranks requiring senate confirmation (O-6 and above). L Scrolls are 2LT -> 1LT promotions (i think CW2 promotions too but not sure). W Scrolls are warrant officer promotions. I haven't seen D or T scrolls on any of the updates available to me so i wouldn't be able to help out there. Hope this helps sir, and also definitely hit up your senators about supporting Senate Bill 4272, which focuses on overhauling the FEDREC system including requiring promotions to be backdated NLT 60 days after the state submits the packet to NGB.