The process of allocation is same and based on the ranks only but only catch here is that only those are eligible who comes and mark their attendance .Open round is for all the seats which left vacant after previous round including surrendered/resigned and cancelled. Also the category seats are converted into general if there is no eligible category candidate.All the eligible candidates are called for this round. All the student who qualify the exams can be eligible for counselling.
It is offline counseling so you have to go AIIMS Delhi. On the day of counselling first you will mark your attendance and get your documents verified. Then they will make a rank sheet of whoever has come up for counselling.You will be then seated in an auditorium with vacancies displayed on the screen.One by one rank wise candidates will be called up on stage and there you’ll pick up whatever you want from the pool of seats.You have to bring your original documents to the counseling or demand draft of something 1 lakh rupee. So if you have joined somewhere you will have to resign and come with all the originals.If you pick up a seat in this round it is considered as ‘confirmed seat’, the Vacancy is then closed for that session and you are liable to pay the bond of some amount of money ( I don’t the numbers exactly may be 3 lakh ).