The d3_1.3_sdk.exe file you have requested: Official Releases / SDKs / DOOM 3 SDK for Windows - 5.21mb is not available. Perhaps try browsing all files for the game Doom III and upload any files you want to share or are missing. This is the only information we could locate:
This new SDK includes the source code for the RoE gamecode. See this page to get more information about it.