diff --git a/Design-Doc%3A-%60level%60-tool.md b/Design-Doc%3A-%60level%60-tool.md
index 11e6b5d..bf7ade9 100644
--- a/Design-Doc%3A-%60level%60-tool.md
+++ b/Design-Doc%3A-%60level%60-tool.md
@@ -13,7 +13,7 @@ To convert a Tiled map and tileset:
 ```
 reskit level -i map.tmx -c mapping.toml --system md --tile-size 2x2
 ```
-Reskit will compile and output a .lvl file which you can then bundle into your game project, as well as a tilemap file formatted to the system defined in `--system`. (More information on .lvl format TBD)
+Reskit will compile and output a .lvl file and .til file which you can then bundle into your game project, as well as a tilemap file formatted to the system defined in `--system`. See below for information on .lvl format.
 
 ## Entity-Component System
 Reskit assumes a best-practice entity-component engine design and the objects defined in your .tmx file effectively serve as the entities. 
@@ -39,6 +39,9 @@ health = {
 }
 ```
 
+## .bin Format (Tiles)
+This is a system-specific binary format of tiles formatted for your target system. Normally you would take this data and DMA it to the video display hardware in your homebrew.
+
 ## .lvl Format
 The .lvl format is output by the `level` tool. It is a binary format ideal for use on a 8-bit or 16-bit game console. All coordinates use (0,0) upper left as an origin. 
 
@@ -74,6 +77,4 @@ For plane A and plane B:
    For (total tiles height):
       For (total tiles width):
          2 bytes: Tilemap ID
-```
-
-(TBD !!)
\ No newline at end of file
+```
\ No newline at end of file