How IPO allotment happens for NII category if it's oversubscribed?

Non Institutional Investors (NIIs)/ High Net worth individuals (HNIs) have a minimum reserve portion of 15% of the shares on offer. For NIIs and HNIs, the allotment is done proportionately. So, if the issue is subscribed 2 times, in that case 50% of the shares are alloted to an investor.