Forty-eight levels in the Thieves' Guild, each with its own sub-levels and requirements.
Generations of thieves, each teaching others the principles of the Guild.
Honor above profit. Skill above chance. Family above all.
Gathered in one spot -- here are all forty-eight levels, plus other insights into the Guild.
The Guild and the Thieves' Guild Academy show up in multiple books in the Tarthian Empire.
Enjoy this overview, with a peek at various books featuring the Guild.

"Thieves' Guild Handbook"

by Kayelle Allen