Here's the reply I got from pilotcredentials:

It seems to be a rating required by mostly Australian and New Zealand airlines. The new system has a lot of air carriers from all over the world and some qualifications/ ratings are added due to their requests.

Here is a sample of a BGT course in NZ: Basic Gas Turbine Courses

If you have any further questions or requests, please don't hesitate to ask!
Sincerely,

PilotCredentials.com Support Team
[email protected]

therefore, I figure I will just ignore it.