Why did 33 lakh voters in Delhi receive EC notices amid SIR?

The Election Commission served notices to 33 lakh people in Delhi amid the ongoing special intensive revision (SIR) of electoral rolls. Of the total, 'not mapped to last SIR' is the biggest reason for the notices, accounting for 42% of the notices. This is followed by name mismatches and age differences, while 59,791 notices have no reason listed against them.