The students between the ages of 16 - 17 years fixed period study 2 years.
(Grade 11 - 12) when students passed this level will be Higher Secondary Education Certificate or Senior School Certificate.
The duration of study in primary and secondary schools is 10+2 years or 12 years (grade 1 - 12) when students finish grade 12 if intending to study in higher education. Will have to pass a Public Exam by the Board of Education state of each state.
For Thai students who graduated from senior high school (University of 6) from Thailand compared to a grade 12 and in applying to study in Higher Education of India. Not sure Public Exam the university will consider the admission by the average throughout the course of the students from Transcript only.