Working for maps in books, dungeon crawl style

In ianuary 2015 i was talking about implementing a map system in a book that you read ingame. Adding lines as numbers in such, like ---- in Quake2\roarke\texts\books.txt didn't work. The game just see them as blank spaces."Ledger of Commands" from the ingame screenshot is just a example, "Index 0" was modified and didn"t worked.
I was thinking that a dungeon crawler thing will work. I think that letters work, but i'm gonna test this (letter stack on top of each other, like below). I like in Dawn of Darkness to keep simple, if it is working.
------------0-----------
l                              l         0 - windows
l             x               l         l - wall
l                              l         x - treasure
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