The G110 course is a beginner's 1 course that consists of 1st to 50th of the G100 lectures.
The G 120 course is a beginner's 2 course consisting of a total of 50 sessions from 51 to 100 of the G100 lectures.
The G210 course is an intermediate 1 course consisting of 50 sessions from 1st to 50th of the G200 lectures.
The G220 course is an intermediate 2 course consisting of a total of 50 sessions from the 51st to the 100th of the G200 lectures.