Regarding Minority Educational Institutions

Article 30 of the Indian constituition guarantees rights of both linguistic and religious minorities the right to start their own educational institutions. But the word 'Minority' is not defined anywhere in the constituition. So what constitutes a minority in India? Can an unaided minority institution (Not receiving any state aid) admit students completely from their own community? There were some people who said to me that minority institutions can only reserve 50% of their seats to their community members. If that is the case, CMC Vellore an unaided minority institution reserves almost 85% of seats (Note: I have no grudge against CMC for that, if not I appreciate their service). As one among the general public , I wanted to know the legal nitigrities backing up these claims of various minority institutions across the country. Thank you!