There is an industry screening and financial screening (max 30 % interest bearing debt - max 30 % cash and interest bearing receivables - max 5 % non permissible income model) that is further narrowed down to the 30 biggest companies listed (details HERE).
Unfortunately, the index apparently only targets the interests of Turkish investors, since the website uniquely caters for a Turkish speaking audience.
To give you an idea of the initial industry spread, see hereunder:
