For admission to most undergraduate courses in India, the eligibility criteria typically include passing Class 12 or an equivalent examination from a recognized board. Here's how it applies to your query:

1. Age Limit :

   • Most universities and colleges in India do not have a strict upper age limit for admission to undergraduate programs, but some professional or competitive exams (like NEET, JEE) may have specific age criteria.
   • It is best to check the admission guidelines of the specific course or institution you're interested in.

2. Eligibility of BOSSE (Sikkim) :

   • BOSSE (Board of Open Schooling Skill and Education) is a recognized open schooling board in India.
   • If BOSSE is recognized by the Association of Indian Universities (AIU) or the National Institute of Open Schooling (NIOS), its certificates are generally accepted for admission across universities and colleges in India.
   • Confirm recognition with the institution where you plan to apply.

Recommendation:

Contact the admission office of your desired institution to clarify specific eligibility criteria regarding open schooling and age.