Figured out a lot of the 19X and 1AX packets. Adding test packet data used in experiments.

FFXIVClassic Map Server/packets/send/player/SetLatestAchievementsPacket.cs

@@ -0,0 +1,23 @@
+using FFXIVClassic_Lobby_Server.packets;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace FFXIVClassic_Map_Server.packets.send.player
+{
+    class SetLatestAchievementsPacket
+    {
+        public const ushort OPCODE = 0x01A3;
+        public const uint PACKET_SIZE = 0150;
+
+        private byte[] mainstoryFlags = new byte[7];
+        private byte[] classFlags = new byte[2*17];
+
+        public static SubPacket buildPacket(uint playerActorID)
+        {
+            return null;
+        }
+    }
+}