As he said, ID itself is going to be a random number. But, how random? I suppose we will surely create non-sequential, random numbers from a large and sparse domain (total set of all possible numbers with a particular number of digits). We surely don't want one up numbers for everyone in a village, do we? Why Random? We believe that this number should not be derived from any personal information.
Should it have alphabets too? We decided not to have alphabets (and hence Nandan's reference to number). It is just easier since most folks in India don't read English and alphabets just look like another picture to them!! We can as well use a picture of an elephant or a flower, they wouldn't care. Numbers are also tough for pure native speakers. But, we need to make some decision, I suppose.
How big the number should be? Especially if we want non-sequential, non-reusable, random number to cover for next 100 years?! World population is predicted to be at around 9 billion in next 30-40 years, if we have more than about 12 digits, we should be really good. We are still in design. So, no details I can share yet.
Now comes the real fun part. Everyone wants (especially our VVIPS) an "interesting" number. What interests them can be different too. For example, I have heard that no one wants a number that adds up to 8 in Tamil Nadu for some numerology related issue. This can be daunting if we have all these people coming back and requesting for another number. What about other "good looking" numbers such as 1234... or 1111... etc. If we can't avoid VVIPS insisting on these, may be UIDAI can officially "sell" these special numbers and make some money!!
In India, we seem to find a meaning in a random number. So, it's going to be a challenge indeed!