Hi there, 

According to the latest updates, students from open schools or non attending schools can write the AIIMS examination. 

Not only that, to be able to write AIIMS you must fulfil the whole eligibility criteria. 

Here's the link that might give you more relevant information: 

https://www.google.co.in/amp/s/medicine.careers360.com/articles/aiims-mbbs/amp

Hope that helps. Please feel free to post any further questions on our platform.

Wishing you luck!