From the TLG website (accessed 2014-10-07):
This site is the result of a collaboration between the Lexikon zur byzantinischen Gräzität (LBG) published by the Austrian Academy of Sciences (Die Österreichische Akademie der Wissenschaften) and the Thesaurus Linguae Graecae® (TLG®) at the University of California, Irvine.
The LBG is the foremost lexicographical resource in Byzantine Studies mainly covering the period from the 4th to the 15th century A.D. taken from more than 3,000 texts. Seven fascicles have appeared to date, with one more scheduled to appear in 2016. When completed the dictionary will consist of more than 2,000 printed pages, containing approx. 80,000 lemmata.
Unlike the majority of the content of the TLG, the LBG, which appeared in October 2014, is freely available for all users to browse and search online. The TLG and the Austrian Academy of Sciences Press reserve all rights, however, and no re-use, downloading or copying is permitted.